I had some jigsaw blades lying around. I cut the end off (diagonally, to leave a sharp point) with a wire cutter. Then I sandwiched it between two sticks of wood to make a handle and wrapped it up with duct tape. It works really well. Surprisingly well, actually. There's only two problems, one of which is fixable.
- The saw blade isn't long enough. I was able to cut all the way through the pumpkins in most places, but some spots I had to go back over with a knife. A longer blade shouldn't be too hard, though too much longer and it will have to be thicker, which makes fine cuts harder.
- Pumpkin shavings are emitted, which collect on the surface, obscuring (or even erasing) the lines drawn there. That said, none of the three of us had any major problems with it. In my case, I just worked in a consistent pattern so that I wasn't dropping goop on places I'd need to see later.
OK, this isn't my personal pumpkin--it's a collaboration between Number Two and I. But it shows we tried.
Pumpkin PI, get it? PI (=PIE)??
You don't get it.