referring now to fig1 a - 9 , a receptacle 10 is disclosed and illustrated to be more amenable to interior cleaning and drying than a typical receptacle . in particular , the receptacle 10 can include at least one sidewall 12 defining an open end 14 , where the receptacle 10 is designed to surround and contain a fluid beverage or other material . the receptacle 10 is eversible , wherein the term “ eversible ” is used herein to describe a receptacle capable of being reversibly “ turned inside out ”, transforming the receptacle 10 between a material holding conformation 10 a and an everted conformation 10 b for ease of cleaning and drying “ interior ” surfaces 12 a of the material holding conformation . in other words , the everted conformation of the receptacle 10 enables facile cleaning and drying of a first surface 12 a which is interior in the material holding conformation opposite from an “ exterior ” or second surface 12 b which faces outwardly in the material holding conformation 10 a . the receptacle 10 can be composed substantially of a material which possesses a sufficient young &# 39 ; s modulus and sidewall 12 thicknesses to avoid substantial transient deformation of the sidewall 12 under the force of weight of the receptacle 10 . the term “ receptacle ”, as used herein , can refer to a container including at least one sidewall 12 defining at least one open end 14 . the container or receptacle 10 can be capable of partly surrounding and thereby containing a material or substance . the material or substance so contained can be a liquid , such as a beverage or other liquid , a solid , a gas , or any mixture or other combination of solid , liquid , and / or gas , or any intermediate states thereof . the receptacle 10 can be eversible . when a substance contacts the first surface 12 a of the receptacle 10 when the receptacle 10 is in the first stable state 10 a , the receptacle can be said to be containing the substance or housing the substance . the term “ eversible ” as used herein , can be defined as the receptacle being completely “ turned inside out ”. the term “ eversible ” as used herein , can be further defined as the receptacle 10 being reversibly transformable between two stable conformations , wherein an interior surface and an exterior surface are reversed with respect to one another . in the first stable conformation 10 a , the receptacle can have a material contacting surface 12 a facing inward , and a second surface 12 b facing outward . in the second stable conformation , the material contacting surface 12 a faces outward , and the second surface 12 b faces inward . any transformation of the receptacle 10 from the first stable state 10 a to the second stable state 10 b , or vice versa , can be referred to as an eversion . any multiplicity of such eversions can be referred to as repeated eversions . the receptacle 10 can also be resilient . the term “ resilient ”, as used herein , can be defined as the receptacle 10 being resistant to permanent deformation . the term “ resilient ” as used herein can be further defined as the receptacle 10 having a tendency to return to one of the two stable conformations , if deformed . the term “ resilient ” as used herein can further be defined as the receptacle 10 having a tendency to resist deformation , permanently or transiently , due to a weight of the receptacle 10 . the resilience of the receptacle 10 can be described in terms of yield strain , which as used herein can be defined as the stress or force at which the sidewall 12 begins to deform . specifically , the sidewall material can be described in terms of fatigue failure . in such cases , the term “ fatigue failure of the sidewall material ” can refer to the situation where eversion , or repeated eversions , results in permanent deformation of the sidewall material . the receptacle 10 can also be described in terms of fatigue failure . the term “ fatigue failure ” as used herein , can refer to the situation where eversion , or repeated eversions , results in permanent deformation of the receptacle 10 . the term “ capping element ” 16 , as used herein , can be defined as a physical structure reversibly engageable with the open end 14 of the receptacle 10 . the capping element 16 at least partially covers the open end 14 of the receptacle 10 , and at least partially inhibits the exit of any contained material from the receptacle 10 . the capping element 16 can comprise at least one surface , wherein the surface is capable of being attached to the open end 14 of the receptacle . such a surface can be referred to as an “ attachable surface ”. when attachment of the capping element 16 to the open end 14 of the receptacle 10 results in formation of a fluid tight seal , it can be said that the receptacle is “ sealingly engaging ” the capping element . the term “ attachment member ” 30 , as used herein , is defined as at least one physical structure facilitating engagement of the capping element 16 to the open end 14 of the receptacle 10 , or tending to inhibit disengagement of the capping element 16 from the engagement member 30 . the receptacle 10 can include a sidewall 12 made substantially of an elastomeric material . the term “ elastomeric ” is well known to those skilled in the art . as used herein , “ elastomeric ” or “ elastomers ” can include resilient polymeric materials having a young &# 39 ; s modulus of between approximately 1 megapascal ( mpa ) to approximately 7 megapascal ( mpa ), inclusive . young &# 39 ; s modulus , also known as tensile modulus or elastic modulus , also sometimes referred to as the modulus of elasticity , is a measure of stiffness of an elastic material . young &# 39 ; s modulus is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which hooke &# 39 ; s law holds , which states that the displacement of a spring is in direct proportion with a load applied to the spring as long as the load does not exceed an elastic limit of the material . young &# 39 ; s modulus can be experimentally determined from the initial , linear slope portion of a stress - strain curve created during tensile tests conducted on a sample of the material . by way of example and not limitation , suitable elastomeric materials can include varieties of silicone , or thermoplastic elastomer ( tpe ), or thermoplastic polyurethane ( tpu ), or latex rubber . suitable varieties of silicone can include silicone rubber , liquid silicone rubber , fluorosilicone rubber , silicone - modified ethylene propylene rubber , silicone polyester resin , silicone alkyd resin , silicone epoxy resin , and any combinations thereof . when the sidewall 12 is made of an elastomeric material , this can be referred to as an elastomeric sidewall . a capping element 16 can be made substantially of an elastomeric material . alternatively , the capping element 16 can be made substantially of a rigid material . the term “ rigid ”, as used herein , can be defined to refer to a material which does not deform during typical use , and can possess , but need not necessarily possess , a young &# 39 ; s modulus of greater than approximately 1 gigapascal ( gpa ), inclusive . the receptacle 10 as disclosed herein can be made substantially of an elastomeric material , and can include inserts 45 , as best seen in fig8 , of a rigid or semi - rigid material . the term “ semi - rigid ”, as used herein , is defined to refer to a material with a young &# 39 ; s modulus of greater than approximately 7 megapascal ( mpa ) and less than approximately 1 gigapascal ( gpa ), inclusive . the inserts 45 can be completely embedded within the receptacle sidewall 12 of the receptacle 10 . individual inserts can be annular in shape and can extend along an entire periphery or perimeter of the receptacle containment element . inserts 45 can be included in any number , and with any spacing between inserts . by way of example and not limitation , the inserts can have equidistant spacing with respect to one another . the receptacle 10 can include a sidewall 12 defining an open end 14 , and an end wall 20 opposite the open end 14 . typically , the sidewall will be contiguous to , or directly adjoining the open end . if an end wall is present , it will typically be contiguous to , or directly adjoining the sidewall . the phrase “ containment wall ” can be used to refer to either the sidewall , or to the sidewall and the end wall together . the end wall 20 can include an indentation 22 in the end wall 20 . the indentation 22 can extend inwardly with a conical shape or can include any other shape , by way of example and not limitation , such as semi - spherical , cylindrical , pyramidal , or trapezoidal . when the shape of the indentation is conical , it can be referred to as a “ conical indentation ”. the end wall 20 can include an eversion handle 24 . the term “ eversion handle ” 24 , as used herein , is defined to refer to areas 24 a of the sidewall 12 or end wall 20 possessing localized increased thickness relative to other portions of the sidewall 12 or end wall 20 , and can be used for facilitating manual eversion of the receptacle 10 . the receptacle 10 can include one or more buckle points 26 , as best seen in fig6 , and 15 , formed integrally with the sidewall 12 . the term “ buckle point ” 26 , as used herein , can be defined to refer to a designed in transition point to a decreased thickness region 26 a relative to other portions of the sidewall 12 where the bottle will tend to strategically deform , making eversion easier . if one or more buckle points 26 are provided , the one or more buckle points 26 would tend to be a region 26 a , as best seen in fig6 , first to deform during eversion of the receptacle 10 . an additional embodiment of receptacle 10 , as best seen in fig1 - 15 , can include one or more buckle points 26 , with a continuous annular protrusion 49 a extending outwardly from the non - containing surface 12 b , as best seen in fig1 - 12 , or a discontinuous annular protrusion 49 b , as best seen in fig1 and 15 , both of which can mate contiguously or in an interrupted manner with decoupling ledge 50 on attachment member 30 . a decoupling ledge 50 can be placed on the sidewall of engagement member 30 , as best seen in fig1 and 13 , or be formed by the lower edge of engagement member 30 , as best seen in fig1 and 15 . this annular protrusion 49 and decoupling ledge 50 will herein be referred to as a “ decoupling point ” 51 . this decoupling point 51 serves to increase the ease of eversion of receptacle 10 by ensuring the buckle point 26 occurs in the desired location . additionally , in the case of negative internal pressure within receptacle 10 due to external suction , or the evacuation of liquid , the decoupling point 51 can serve as a means to reduce internal volume thereby equalizing pressure without the need to draw external air volume into receptacle 10 . this quality is particularly useful in the nursing bottle application because no venting between the inside and outside of receptacle 10 is required for fluid delivery , although external venting could be used . the decoupling point 51 location and number can vary based on bottle height and diameter . this decoupling point 51 is particularly important for bottles with a diameter to height ratio ( diameter / height ) of less than 1 . containment holding protrusions 52 can also be included on attachment member 30 , as shown in fig1 . the containment holding protrusions can create an interference fit between attachment member 30 and second surface 12 b of receptacle 10 . containment holding protrusions 52 would typically , but not necessarily , extend 1 millimeters ( mm ) to 5 millimeters ( mm ), inclusively , from the attachment member surface . additionally , these containment holding protrusions could also be included on second surface 12 b of receptacle 10 . it should be recognized by those skilled in the art that a continuous or discontinuous protrusion extending along a periphery of the surface 12 b of the sidewall 12 can create and define a corresponding change in wall thickness and / or a corresponding localized change in young &# 39 ; s modulus , either of which can be referred to herein as a “ buckle point ” or “ buckle region ” of the container or receptacle . in other words , a continuous or discontinuous protrusion extending along a periphery of the surface 12 b of the sidewall 12 can by definition be a “ buckle point ” or “ buckle region ” even when the wall thickness is otherwise considered constant thickness and / or even when the young &# 39 ; s modulus is otherwise considered constant . the receptacle 10 can include stability lip 54 , as best seen in fig1 and 15 . the term “ stability lip ” 54 , as used herein , can be defined as an outward protrusion along end wall 20 . stability lip 54 can be used to reduce the tendency of the receptacle 10 to unexpectedly fall over , for example , while resting on an uneven surface or when disturbed by outside forces . the receptacle 10 can include an annular engagement lip 28 , as best seen in fig2 and 4 . the term “ engagement lip ” 28 , as used herein , can be defined to refer to an outward protrusion 28 around the perimeter 14 a , as best seen in fig1 a , of the open end 14 of the receptacle 10 . the engagement lip 28 can assist in securing an attachment member 30 to the receptacle sidewall 12 . the engagement lip 28 can additionally include a sealing lip 29 as best seen in fig5 . the term “ sealing lip ” 29 , as used herein , can be defined to refer to an upward protrusion 29 a , or downward protrusion 29 b around the perimeter of the engagement lip 28 . the sealing lip 29 can tend to cause increased pressure between a capping element 16 and the open end 14 of the receptacle 10 , when an attachment member 30 is engaged . an annular flange 34 can be provided on a capping element 16 . the term “ annular flange ” 34 as used herein , can be defined to refer to a ring - shaped protrusion 34 a around the base of the capping element 16 which holds an attachment member 30 in position to effect reversible attachment of a capping element 16 to the receptacle 10 . the receptacle 10 can include an open end 14 defined by one or more sidewalls 12 , and an end wall 20 , wherein a thickness of the end wall 20 is greater than a thickness of the sidewall 12 . by way of example and not limitation , a thickness of the end wall 20 can be approximately 2 millimeters ( mm ) and a thickness of the sidewall can be approximately 1 . 5 millimeters ( mm ). in other words , the buckle point 26 or region 26 a can include a first wall thickness of approximately 1 . 5 millimeter ( mm ), and other portions of the containment walls include a second wall thickness of at least approximately 2 millimeter ( mm ). alternatively , the buckle point 26 or area 26 a can be defined by a region of the containment wall having a first young &# 39 ; s modulus less than a second young &# 39 ; s modulus of other portions of the containment wall . the receptacle 10 can be configured to enclose a beverage . when in a first stable conformation 10 a , a first surface 12 a of the receptacle 10 can face inwardly toward an interior of the receptacle 10 . when in a second stable conformation 10 b , the first surface 12 a can face outwardly toward an exterior of the receptacle 10 to be particularly amenable to cleaning and drying after eversion of the receptacle 10 from the first stable conformation 10 a ( as best seen in fig1 a ) to a second stable conformation 10 b ( as best seen in fig1 c ). the first stable conformation was referred to above as the material holding conformation , and can also be referred to as the normal stable conformation . the second stable conformation was referred to above as the everted conformation , and can also be referred to as the everted stable conformation . by way of example and not limitation , the receptacle 10 can be made in the form of a nursing bottle , or other beverage container for general beverage storing or drinking use . the eversion of the receptacle 10 can facilitate cleaning milk , baby formula , protein powder , or other liquid or solid beverage residues from the beverage contacting surface 12 a of the receptacle 10 . referring now to fig1 a - 1c , a receptacle 10 is illustrated undergoing reversible eversion , between a first stable conformation 10 a and a second stable conformation 10 b . by way of example and not limitation , fig1 b illustrates a possible eversion midpoint 10 c , between a normal use first stable conformation 10 a shown in fig1 a and complete eversion stable conformation 10 b shown in fig1 c used for cleaning and drying . the possible eversion midpoint 10 c demonstrates a possible manner of eversion , but does not imply a required direction , sequence , or manner of the manual eversion process . the receptacle 10 includes a sidewall 12 defining an open end 14 . the sidewall 12 can include a contained substance - contacting surface 12 a and a non - contacting surface 12 b . in the first stable conformation 10 a , the contained substance - contacting surface 12 a faces inwardly toward an interior of the receptacle 10 , while the non - contacting surface 12 b faces outward . in the second stable conformation 10 b , the contained substance - contacting surface 12 a faces outward and the non - contacting surface 12 b faces inwardly toward an interior of the receptacle 10 . referring now to fig2 , a cross - section of sidewall 12 is illustrated . the receptacle 10 can include an end wall 20 . the end wall 20 can include an indentation 22 , by way of example and not limitation , such as of conical shape . the sidewall 12 can include a buckle point 26 , an engagement lip 28 , and sealing lip 29 . referring now to fig3 , by way of example and not limitation , the receptacle 10 can be made in the form of a nursing bottle 10 . the receptacle 10 can include a capping element 16 and an attachment member 30 . the capping element 16 can be formed in the shaped of a nipple . alternatively , the capping element 16 can be formed in the shape of a disk , a cylinder , or any other shape which would serve the purpose of inhibiting exit of contained material from the receptacle 10 . fig3 additionally illustrates a protrusion 18 on the capping element 16 to help in taking the cap element 16 on and off from the receptacle 10 . the protrusion 18 illustrated in fig3 is incorporated into the attachment member 30 . additionally , receptacle 10 can include an optional one - way valve to diminish negative pressure inside the receptacle created as receptacle contents are evacuated , and can alternatively be incorporated into a receptacle sidewall 12 , end wall 20 , indentation 22 , or capping element 16 . referring now to fig4 , a longitudinal detailed cross - section view of the receptacle 10 of fig2 is illustrated . by way of example and not limitation , as illustrated in fig4 , the attachment member 30 can include two sleeves 30 a , 30 b with complementary threading 33 . one sleeve 30 b can engage with the receptacle 10 , while the other sleeve 30 a can engage the capping element 16 . alternatively , as illustrated in fig5 , the attachment member 30 can include a single threaded sleeve , wherein the threading 33 a on the attachment member 30 is complementary to threading 33 b on the capping element 16 . still referring to fig5 , the attachment member 30 can include a single threaded sleeve , which includes threading 33 a , the threading 33 a being complementary to threading 33 b which is directly molded onto the capping element 16 . referring now to fig6 , a detailed cross section view of the sidewall 12 of the receptacle 10 is shown . the illustrated area depicts a buckle point 26 in the sidewall 12 . the buckle point 26 can be approximately 1 . 5 millimeters ( mm ) thick , while other regions of sidewall 12 can be approximately 2 mm thick . in other embodiments , buckle point 26 can have a first young &# 39 ; s modulus less than a second young &# 39 ; s modulus of other regions of sidewall 12 . the buckle point 26 can extend along an entire periphery or perimeter of the receptacle 10 to define a buckle region 26 a . referring now to fig7 , the receptacle 10 is illustrated in a first stable conformation 10 a with an attachment member 30 , and a capping element 16 composed substantially of rigid material . the capping element 16 can include a protruding passage 40 defining an aperture and a removable cap 41 . the protruding passage 40 can serve as an exit point for receptacle contents , for example for drinking a beverage from the receptacle . the removable cap 41 can serve to reversibly cover the protruding passage 40 to thereby reversibly prevent evacuation of receptacle contents . referring again to fig3 - 4 , the capping element 16 can have a nipple shaped surface with an outwardly projecting annular flange portion . an attachment member can include a first rigid sleeve 30 a having an inwardly - facing threaded portion 33 adjacent one end . the first rigid sleeve can be of a size to encircle the nipple shaped surface while engaging with the annular flange portion of the capping element 16 and fit over the open end 14 of the containment element 10 . a second rigid sleeve 30 b can have an outwardly - facing complementary threaded portion 33 and can be of a size to be fit within the threaded portion 33 of the first sleeve 30 a , such that when the threaded portions 33 of the first and second sleeves 30 a , 30 b are juxtaposed with respect to one another , and the threaded portions 33 of the first and second sleeves 30 a , 30 b are engaged and tightened via rotary displacement , a fluid tight seal is formed between the annular flange portion of the capping element 16 and the open end 14 of the containment element 10 . referring to fig7 - 8 , the capping element 16 can have a rigid body with a first threaded portion . a protruding passage 40 can define an aperture formed in the rigid body . a cover element 41 can be provided for reversibly covering the protruding passage 40 defining the aperture . the covering element 41 can be attached to the capping element 16 . an attachment member 30 can have a rigid sleeve with a second threaded portion 33 b complementary to the first threaded portion 33 a . the sleeve can be of a size to fit over the open end of the containment element , such that when the threaded portions of the capping element 16 and attachment member 30 are engaged and tightened via rotary displacement , the capping element 16 and the open end 14 of the containment element 10 are reversibly brought into contact . referring now to fig8 , a detailed longitudinal cross - sectional view of sidewall 12 of the receptacle of fig7 is illustrated . the receptacle sidewall 12 can include inserts 45 of rigid material . as used herein , the phrase “ inserts of rigid material ” can be defined as referring to annular inserts of material , fully embedded within the receptacle sidewall 12 , and composed substantially of material which is rigid or semi - rigid as defined above . such rigid inserts can improve the structural stability of receptacle 10 when in stable conformation 10 a . it should be recognized that inserts 45 can be used in the sidewall 12 of any configuration of the receptacle 10 , and are not limited to use in the specific sidewall configuration illustrated in fig7 and 8 . referring now to fig9 , a detailed longitudinal cross - sectional view of sidewall 12 of a receptacle 10 is depicted . the receptacle sidewall 12 can include sidewall ridges 46 . the phrase “ sidewall ridges ” as used herein can be defined to refer to annular regions of increased sidewall thickness , relative to other portions of the sidewall 12 , and which are substantially parallel to the perimeter 14 a of the open end 14 of the receptacle 10 . the sidewall ridges 46 can improve the structural stability of receptacle 10 when in the stable conformation 10 a , or can facilitate holding of receptacle 10 . it should be recognized that the sidewall ridges 46 can be used in the sidewall 12 of any configuration of the receptacle 10 and is not limited to use in the specific sidewall configuration illustrated in fig9 . referring now to fig1 - 12 , a perspective view , a cross sectional view , and a detailed cross sectional view , respectively , of an additional embodiment of a general use bottle , similar to the general use bottle of fig7 , is depicted . in this embodiment , the attachment member 30 , with threaded portion 33 b complementary to the first threaded portion 33 a , seen clearly in fig5 and 7 , is extended to include “ eversion cutouts ” 48 and “ containment element pull down cutouts ” 47 , as best seen in fig1 , and decoupling ledge 50 with continuous annular protrusion 49 a to form decoupling point 51 at buckle point 26 , as best seen in fig1 . decoupling point 51 ensures that buckling occurs at the desired buckle point 26 rather than elsewhere on the bottle , increasing ease of eversion . in this same embodiment , eversion cutouts 48 can also be used so the user can continue to everse containment element 10 upwardly towards the open end 14 of the receptacle , as in fig1 a - 1b , by reaching through eversion cutout ( s ) 48 and pushing containment element 10 . to insert containment element 10 back into attachment member 30 , containment element pull down cutouts 47 can also be included such that the user can grab and pull containment element 10 downward , until containment element 10 is secured into attachment member 30 via opposing forces created at the decoupling ledge 50 with continuous annular protrusion 49 a and engagement lip 28 , as seen in fig5 . referring now to fig1 , a cross - sectional view of extended attachment member 30 , similar to the attachment member 30 shown in fig1 , is depicted . containment holding protrusions 52 can also be included on attachment member 30 . the containment holding protrusions create an interference fit between attachment member 30 and second surface 12 b of receptacle 10 . these can be used to more securely hold containment element 10 with respect to attachment member 30 . containment holding protrusions 52 would typically , but not necessarily , extend 1 millimeter ( mm ) to 5 millimeter ( mm ), inclusively , from the attachment member surface . additionally , these containment holding protrusions could also be included on second surface 12 b of receptacle 10 or on only second surface 12 b of receptacle 10 . referring now to fig1 - 15 , a perspective view and a cross sectional view , respectively , of an additional embodiment of a nursing bottle is provided . in this embodiment , the attachment member 30 , with threaded portion 33 b complementary to the first threaded portion 33 a , seen clearly in fig5 , is extended to include “ containment element pull down cutouts ” 47 , as best seen in fig1 , and decoupling ledge 50 with discontinuous annular protrusion 49 b to form decoupling point 51 at buckle point 26 , as best seen in fig1 . also included in this embodiment is a stability lip 54 . stability lip 54 can be used to reduce the tendency of the receptacle to unexpectedly fall over , for example while resting on an uneven surface or when disturbed by outside forces . referring now to fig1 - 17 , attachment member 30 can substantially or completely surround the non - containing surface 12 b . there can also be a designed in air gap 53 , typically , but not necessarily , between 2 millimeters ( mm ) and 5 millimeters ( mm ) in width , inclusive . this can create a thermally insulative enclosure around the containment element via a column of static air between non - containing surface 12 b and attachment member 30 . this serves to aid in maintaining the current temperature of the material being held by material contacting surface 12 a and eliminate condensation from forming on the exterior surface of attachment member 30 when cold liquids are being stored in containment element 10 . while the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment , it is to be understood that the invention is not to be limited to the disclosed embodiments but , on the contrary , is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims , which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law .
a receptacle has at least one elastomeric sidewall with a contoured non - linear shape defining a container with a predetermined volume for housing a substance to be contained . the at least one sidewall includes a substance - contacting surface . the receptacle is fully reversibly eversible to transform between a first stable conformation with the substance - contacting surface facing inward and a second stable conformation with the substance - contacting surface facing outward allowing for facile cleaning and drying of the substance - contacting surface . the at least one elastomeric sidewall possesses sufficient structural strength to stand upright in the first and second stable conformations without extraneous support . the receptacle can include a cap and an attachment joint for securing the cap to the elastomeric receptacle .