They were for sale, back in the 70s and 80s.
I put a piece of masking tape on the baseplate and write the film type and E.I. with a Sharpie. Masking tape peels off cleanly, as long as you don't leave it there for a year or two.
Hmmm. Another worthy idea. And if I used painters tape (which is supposedly even less sticky than masking tape) it should be even less of a problem.