text: Then I redesigned DIYTIL305 PCB to make assembly process easier (bigger led pads, adjusted solder paste expansion) and tweaked dimensions to mimic the original.
  Next up was assembly itself. First I made one display with red leds to see if changes to the new design are good. Success! First board passed the test with all leds soldered correctly. That meant I could move to other boards(colour variations).
  0201 leds are only available in red, green, white, blue, orange and yellow colours. I used all colours except yellow because it is not that much different from orange. White leds were hardest to place because they don't have transparent case, so they can't be visually inspected for correct orientation.
  Polycarbonate filters(CR-39) were used as display covers. They were glued using 3M VHB 4910 double sided tape. Transparent, acrylic foam tapes are used where clear attachment of two materials is needed and therefore are ideal for this application.
  Glueing display covers was straightforward, but since I didn't have access to laser cutter I cut them by hand using box cutting knife(scoring and snap method). They aren't the prettiest, but for a few prototypes they are good enough.
  This week I assembled few DIYTIL305 modules. Main problems were: Solder paste that wouldn't go through stencil, leds sticking to tweezers and not being aligned with footprint after reflow process.
  First problem was solved by getting finer grain solder paste (in future led footprint will be adjusted). Solution for second problem was to clean tweezers with rubbing alcohol multiple times during assembly process and re-heating leds with hot air gun with addition of flux so they align with footprint (some leds are still misaligned).
  Afterwards I did some comparison between DIYTIL305 with red transparent acrylic and original TIL305 (last two pictures). In those pictures DIYTIL305 consumed 1.27mA and TIL305 15.78mA.
  PCB - PCB is 0.8mm so that I can easier match TIL305 dimensions (PCB + diffuser). Kingbright APG0603 series of leds is used (0201 Imperial code). Black solder mask is used to provide better contrast of leds with background. Exposed copper traces on PCB as a throwback to original part.
  Pins - Machined header pins with broken plastic guard are used. Compatible with breadboards and IC sockets, cheap, accessible, gold plated. Also 1.27mm pin header can be used for lower mounting heights when soldered.
  LED Diffuser - Used to make the light from leds more uniform and distinguishable. I will approach to this from three different angles:
  Laser cut acrylic (suggested by Dave's Dev Lab). Example of acrylic that can be used showed on image below.
  According to datasheet dots on TIL305 are arranged on 0.05"(1.27mm) grid. With that information I can now measure the size of a single dot. On the picture below each increment of scale represents 0.1 mm. It means that single dot is 0.4x04mm. I thought incorrectly that they were 0.6x0.6 (drawing from datasheet is more symbolic than actual representation of the part).
  While researching TIL305 I discovered TIL302. It shares same package as TIL305 but is configured as seven segment, unlike TIL305 which is 5x7 matrix. I had to get one so here are some pictures:
  8418 means 18th week of 1984. This was the most used date code for components. I don't see where you're going, aren't you reinventing the wheel ?
  Plan is to see how good I can replicate TIL305 display to see if it is viable to make my own custom modular displays for future projects(watches - see my past projects).
  I remember these displays well - but my favorite was always the HP hex display - 5082-7340. I still have a bunch here in the garage somewhere. Probably a few of these TIL displays as well.
  This is a really neat idea. You should have no problem making the PCB itself (even finding proper legs by looking into the OSHchip which actually had pins fabricated for a use just like this:
  In my mind the trick is to get the enclosing material to come out really nice and transparent, flat, etc. Any thoughts on approaching that?
  you can get 2mm transparent red acrylic that could be cut and shaped with a laser cutter(ponoko.com) to fit onto the PCB. that should fit well and provide enough transparency to look nice. i am wondering if using white LEDs instead of red would look better...
  White could look better but would lift the minimum working voltage up as well. Red is somewhere around 2V, white is 3 to 3.5V.
  But there are superbright red LEDs available which are so intense they should look fine under red plexiglass/acrylic.
  That is great idea! In fact I actually have one piece of transparent led lens filter(used in photography) that might do the job. Those filter are 10x10x0.18cm and go for 1$ on eBay.
  My original plan was to use transparent red filament printed on FDM printer(did some test prints) or transparent resin printed on stereolithography printer. I will see what is my best option. More info about this in future update.
  I must say, those TIL displays are crisp as hell and look totally nice, but even 0402 LEDs are double the width of those thin TIL ones...