This is a 3-in-one button dial that allows a player to use one hand to control both left/right rotation of a turret or arm as it is twisted accordingly... and also fires if you press it down.
This short video shows assembly and action:
This is not a quadrature-encoded spinner nor an 8-directional knob! It is simply a bipolar toggle dial with a push button action built in as well. Ideal for MAME versions of Ikari Warriors, Tron and many others.
The hole that this fits in is a little smaller than your standard 1 1/8" (29.5mm) hole for arcade machines... it can fit between 24mm and 27mm holes (I only work in metric...)
The Housing is the only piece that needs to be printed with external support. The rest just prints on the base plate without any kind of raft/support.
Enjoy and I'd love to hear your feedback!
Nov 18th, 2015 update: Added shim.stl for adjusting to a 1 1/8" hole. You'll need one for the topside and the underside of the control panel.