Iowa,
Just my two cents, as I am the new guy. I've had some luck with a few box call lids running them over a bench-top belt sander lengthwise. Just rock them side to side and the arch will come together. It works for me as I don't have a bandsaw, and a low grit belt hogs away a lot of material, which makes for fast work (especially with the maple). I run the top over a precision plate, that way I can check to see if I have any dips or divots. I thickness the lid, top, and sides with a plane, so no real precision work here. This is no means exact but it gets me fairly close, as I have a cedar/maple box call I'll be putting some miles on this season. Good luck with your call!
