I have noticed references to people using cordless electric drills and cheapo air hammers while building their metal airplane. I'n not saying it can't be done, but if you are going to build a metal airplane, do yourself a favor and buy good tools. They don't have to be new, just good quality. eBay is rife with drills, Desoutter, Dotco, and Copco are good names. Same with rivet guns, just search 3X rivet guns and you get all sorts of hits. You don't need a huge compressor to run these either. I built an aluminum bodied travel trailer at home with a small compressor, probably 10 gallon tank, and it came out just fine. That said, that 10 gallon compressor won't run a die grinder but about 5 secs. I have 5 or 6 air drills, and my favorite is an old Ingersoll-Rand that I found in a pawn shop for $35. Also, spend a little more for a good keyless chuck, after numerous drill bit changes you will be glad you did.