Circles Corner

One diagonal cut across every cell. I blacked out half of each of the 256 pixels from behind, so each 10 mm cell works like a tiny gobo with a hard edge through the middle. Off, the face is blank. On, the hidden half-shapes appear through the diffusion all at once.

It is the simplest mask in the series and the easiest to repeat 256 times, which is part of why it works. The only thing that can break it is bleed. If light from the lit half leaks across into the dark half, the shape is gone. So the black layer behind the white diffusion had to be exactly one millimeter thick, enough for total blackout with no room for the print to get lazy.