Made this to hold cups and tumblers for my girlfriends cup turner. Newer version with a longer hollow bolt to tighten the grips against the inside of the cup. The longer bolt protrudes from the opening of the cup / tumbler which makes it easier to tighten.
The cup turner I made uses 8mm rods, this cup gripper fits the rod perfectly. The bolt is hollow and allows the rod to pass through it. This could be scaled up or remixed to work wooden dowels or smaller diameter PVC pipe.
It uses 6 M3x16, 3 M3x12, and 3 M3x8 socket cap screws.