thin aluminum option - free- use a pop can side
The sides of modern pop (soda) cans are very thin. The dimple with a pin and sand off trick works well for me. Then stick a known scale (paper can work here) negative in your enlarger with the head up high, and then project through the pinhole. Work out the length of the known length on the baseboard, then the measured length of the pinhole to work out what diameter you have made.
The sides of modern pop (soda) cans are very thin. The dimple with a pin and sand off trick works well for me. Then stick a known scale (paper can work here) negative in your enlarger with the head up high, and then project through the pinhole. Work out the length of the known length on the baseboard, then the measured length of the pinhole to work out what diameter you have made.