Excellent idea!! I might just rough it out with a sander and a contour gauge. It'll look more "hand made" that way I guess.
If you go that route, I'd suggest using a power sander of some sort to rough out the shape and fine tune it by hand using a piece of a pool noodle or pipe insulation cut lengthwise with a piece of sand paper with adhesive back stuck to the inside curve. Or you can buy something like these