Originally Posted by
stan
just had a look at the kit pics, seems to be based on a a routed out LP body...
If it were me: I'd decide on a simple back plate design or buy one. An LP one from a kit would be fine and surely someone would have one somewhere, or make a basic rectangular one
Use the plate to mark up the guitar.
Cut out with a dremel or even drill a hole and use a jigsaw within the lines - then use a file and sand paper for final size to get it nice
Then make up the inner trim piece that the plate will rest on and glue it in - job done
Alternatively if the back is thick enough - cut the hole undersized slightly and then fine route an edge around the outside to create a shelf for the control plate : make up a template for the router using the control plate as a guide and double side tape it to the body to route.
Or some variation of that - good luck