That looks deadly. I've been stabbed in the foot twice by fins, but that bad boy would take a leg off.
The leading edge is not sharp, the bumps are smoothly rounded to the foil shape and the fin is definitely safer than a typical thruster fin, the polycarbonate has some 'give' to it as well, stiff and strong but we've bent one over thirty degrees during strength tests.
Roy I'll need to get one to put on my PP retro I've been speaking of on swaylocks. I have been hand foiling a plywood fin with the leading edge bump.. Good god it's hard to do. I think your 3d printing is a pretty solid idea.