This is a design I created tonight. It's based on NEMA17 motors, since I have six of those from an old 3D printer I took apart. The idea is to make it as fully plastic as possible, with as few fasteners as possible (if any). I know the rotations aren't correct yet, just messing with it for the first night. I plan to make it in nylon or carbon fiber nylon. though another filament may be a better choice. the box is the claw.

hidden under the base is a gear with the teeth facing in and a motor driving the gear, plus a base that rides on bearings. The note (not visible) in the center of the base allows wires to travel to the steppers. The idea is to save the expense and complexity of a slip ring by just putting extra wire harness length and letting it twist up to a a few revolutions. eh, it's an idea.

Les