Haven't had time to work on the plane, but I have bought a couple of tools. 😁  I'm kind of a sucker for useful tools.

I have a nibbler, but it's pneumatic and that's a pain...  I recently stumbled across this cool tool which is a versatile nibbler that uses your drill.  Good for cutting circles, curves, etc.  This would have been a better tool to use to cut that notch for the wiring the other day.

I read an article in Kitplanes the other day (from the guy that does HomebuiltHelp) that recommended this tool for cutting straight lines in sheet metal.  Using a straight edge, you just score the sheet a few times with this knife (not going the whole way through) and then just snap it off.  Much cleaner line (and way easier!) than using snips which I think are a real pain to use (especially if it's thick sheet) and don't give you the cleanest lines.