Hmmmmmm
I need the exact same thing as well.
Without thinking, I put my cab's power button on the underside of my control panel right where my hand needs to go to open the access door to the controller plugs of the Xbox inside.
It'd be great if anyone found some flip guards that covered a standard arcade button.
I honestly hadn't even thought of that solution, and was looking instead to just sink the button into the wood, so that it would be flush, but I'd much rather have the cover.
I am going to do me some searchin as well, and will post back any results if I can find any.