Since it sounds like you're limited to strictly plastic parts, based off your post, you may want to make that obvious or you'll get a bunch of responses that include complex assemblies/items beyond the scope of what you're offering.

As far as plastic parts go: Williams drop target sliders - not available AFAIK (except as 3D print stuff) and do wear out, especially the screw holes on the early banks that use the horseshoe contacts, and the same piece fits across a huge year range of games from the very first drop target games into the more modern stuff.

Richard