Hi Jep.
Those polys are excellent.
Here is my version of a litho. No dust to deal with and no screaming spindle. Analog modulated Laser diode on the back of mirrors using PEP to generate the code. You can back light them or not. It will give the same image effect either way. These are not backlit. Only thing you have to do is spray a light coat of clear paint on the back to seal them. The hardest thing is taking a picture of them.
Jeff