I've got a 3/4' thick piece of red oak cut out to the shape of the guitar:
I was preparing to glue it down then carve the top but I discovered today that it has warped. I don't know anyone with a planner large enough for the piece, do I have any other options?
^^^^^^ What Bruce said..A well set up router fixture can be used to flatten almost any size object, people use them to flatten workbenches, a guitar shouldn't be a problem.