I tumbled thousands of slotted 5/8"ish cube Teflon parts for archery so have some experience. I used a plastic media that I haven't seen often. It was a solid color, as in not translucent like most green plastic media I have seen. It was more aggressive than most on aluminum, so I guess you should look for an aggressive plastic media. I think I used the smaller tumbler with an 18" bowl that was gentle, vs the 6' bowl tumbler. Anyway, it tumbled fine, a bit slower than aluminum but it still rounded the edges. Sounds like it is going to be fun digging those parts out of the media.