Creating one-way mirror-like lenses I want to make some kind of lenses.

I want to dye (or buy) a piece of white glass or plastic (whatever works best). However, I still want to be able to see through it - I guess about 80% white and 20% transparent. I only need to see through from one side, so a mesh would probably be a good idea, although it is not the preferred solution.

One side should be dark, the other bright most of the times, and the white side (as perceived from the bright side) should be perceived as white even if the "outer" person is very close to the glass.
The "see-through" from the inner site doesn't have to be as perfect as a two-way mirror. It's okay if the person has to get really close (like the distance of sunglasses), but pinhole glasses won't do it.


The "frosted" look probably would let enough light through but is not see-through.
There are some electric "foils" that can be put on windows, to change it from clear to opaque (by percentage), but I don't think that this is the thing I'm looking for, because I don't need to change the opacity, and they would make the effect reliant on electricity.
Dye could also be the way to go.


How could I solve this problem?

I like the airbrushed part of the visor on Robocop by Legacy Effects: could this be a possibility? How would I do this so it remains a little bit transparent?
If you put clear tape on frosted glass it becomes see-through. 
You could try that if it's meant to be a momentary peek-though situation.



Or you could mostly frost it with white alcohol ink. 
Just leaving enough of an open lattice to achieve a veiled appearance.

I'd think a decent way to accomplish that would be to 
put on some gloves, wad up a small piece of fabric, 
wet it with the alcohol ink, then dab it on the glass. 
Practice on a scrap piece of clear plastic 
a few times to get the technique down, 
like from a 2-liter bottle that you cut apart.

I remember hearing about see-through concrete that had similar properties: link to article