Is there a plastic material thin enough to cut with a utility knife for making masks to go over a light source? Needs to be black and block all light transmission. What thickness should I look for?
I have been trying 3/16 in black foam board for this purpose but the cuts turn out a bit messy and it's easy to make dings in it with too much pressure. I want something I can make once then use for years.
Will 1.5mm thick black ABS plastic work? What about 3/32 inch black EPDM rubber?
You can buy a plastic card material from hobbycraft/model building suppliers, called - un-surprisingly - 'Plasticard'. Comes in various thicknesses and colours include black, which is opaque. Easy to cut, or score and break.
'Plasticard' in the UK or 'Evergreen' in the USA, both brand names for polystyrene plastic card (black or white) usually sold in A4 sheets. If you want to make something rigid 20thou is the least thickness but 60thou is best for very rigid. Ideally glue it with polystyrene glue that you'd use for plastic kits. A sharp knife blade is needed but knife blades can wander when cutting it so only scribe the line first as a guide. You generally don't need to cut all the way through but after you reach halfway it can be 'snapped'.