For a carved top, some people use routers, some use hand-tools, and some use CNC machines. My favorite method, is scoping out a curve, then using a router to rout concentric grooves of different depths, maybe 1/4" to 1/2" wide. You'll need some kind of router attachment to brace the whole unit against the contour of the guitar.. I kinda had to fabricate my own. Anyway, once you have your stairstep-like pattern on the guitar body, just sand or chisel off the ridges.. easy as hell, but be careful around the cutaways, and you probably can't do this with the neck on.