The Bulldog

Built to interface with the XBOX Accessibility Controller, this is one button that will register as just about any of the buttons that interface with the 3.5mm jacks.

This is made from a keyboard switch, so I can make it with a variety of actuation forces and clickiness. 

It doesn't have to be built this way, as I can make it in about any configuration, height, weight, and so on that you'd like. 

I've built some variants with a suction cup so you can attach it to a glass table. Just let me know how you'd like it laid out.