I like Paul's idea. Making planes is not as uncommon as most people would think... the blade profile is pretty easy to create by softening it with a torch first. You can cut the metal with a hack saw, a fine-tooth fret saw or a file. Re-harden the metal by re-heating it and then quenching the hot metal in vegetable oil or spent motor oil. Research/observe the right methodology and safety precautions first so you don't burn down your house or yourself.

You could use an old plane as Paul suggests or make one. It doesn't have to be a work of art since you are probably just tooling Cedar. Here's a compass rabbet plane that I made to help bevel strips; the curvature of the sole is very slight... http://www.chipsandresky.com/cedarstrip/images/compassplane.jpg

www.ChipSandresky.com/lorettaandchip.html