Yeah, I think tools would have to be considered here, maybe as a sub category. I have heard it said that a man is only as good as his tools, and I think that applies very much to RC airplane building. I have always had a problem making slots for hinges. A couple years ago I ran across a tool on the internet to do slots. It is a flat blade shaped like an arrowhead, razor sharp point and fluted on the sides, very sharp. This thing fits in a handle that comes with some hobby knife sets and you simply cut the slot by hand, shoving the point right in the center of where you want the slot and letting the fluted edges cut their way into the balsa. Cuts easily and you can guide it where you want it. Works in even very thin balsa.