Another idea is to create a wood skeleton cp under it.
Take off all your joysticks / buttons / whatever.
place your nice new control panel over a new piece of cheap plywood. 1/2 inch or something strong.
place old control panel on the plywood.
outline the control panel panel.. and draw all buttons on plywood.
next remove the control panel (so we are only talking plywood now).
take all the outline lines in by a bit to make sure that if you cut along it, it will fit inside your cabinet (in an inch if the control panel currently sits on 3/4 plywood.... ie, at the end, that piece can fit in the cabinet.
next...
add space around each button and each joystick so that you can really fit each controller... horizontal buttons need space for both the microswitch and the cables.
you should be liberal to this opening up areas to make it easy to work from under the areas. You are really trying to get a few strips from edge to edge... And basically add stability where it makes sense
next cut them out...
wood glue the parts together.
put it back together...
Note: I had this in the past with a chopped up metal control panel where they kept adding buttons after a few kits added... and after a while, it was to weak to hold up... so they did this..