Is it possible to make a bump key from something other than metal?
whats a bump key ?
Get a blank key from a key cutting place, grab a triangular file. . . . . .these i'Bles should help: https://www.instructables.com/id/How-To-Turn-Ice-cream-Stick-Into-Key/?ALLSTEPShttps://www.instructables.com/id/Key-copy/?ALLSTEPShttps://www.instructables.com/id/Duplicate-Keys-by-Hand/?ALLSTEPS
Depends: how sure are you that your substance won't break off in the lock or shatter when hit? By all means, make one out of PVC, or the PET (?) stuff that they make sodabottles out of. Try it in a cheap padlock or something. If it doesn't break, problem solved. I would worry about fatigue over time, though. So don't use it too many times before making a new one.