I used Lizard Litter, which is crushed walnut shells. I wanted emery for the filling, but could not find any. Somewhere in my internet travels, I read that the metal filings used to blast paint from cars when preparing for a new paint job was what I should use, something like aluminum oxide . I gave up trying to find a place that would sell me the stuff. The little pincushions I made as gifts have worked out okay. I had not thought about nut allergies, but will keep that in mind now.