Last night I was cutting the linings for my violin. At one point, I had a strip of wood about 25mm wide and 2mm thick, and I was cutting it into 7mm strips with an X-Acto knife. Cutting the last strip, which involved holding a metal ruler along its length with my left hand, and cutting with my right. Of course by this time, it was really thin, and I was concentrating on making a nice straight cut, so I didn't see that my thumb was sticking out a bit where it shouldn't be. Found out pretty quick, and I'll have a nice scar as a reminder. Here's a tip, though... CyA glue, which has many uses in modeling but almost none in violin making, was first developed as a liquid bandage for military field use. I'm hoping my use of it here might minimize the scarring, but it's probably too late...