CAD art will print your mask design directly onto a transparency (mylar). You can draw features down to 10 micron resolution.

These mylar masks are flexible, so you need a glass backing for contact printing. Rick has attached the Mylar mask to a 4×4“ glass plate. He uses selotape to secure the mask to the glass plate, with good results. That way he can easily switch Mylar masks and use the same 4×4” glass plate. He purchased the glass from the hobby store near Fred Myers. “You need to make sure you get a fairly thin piece. If you get to thick of a piece of glass you will not have enough adjustment on the aligner to get the correct separation while aligning.”