A photo posted here reminded me of something that I haven't seen mentioned yet. When fabricating with metal it is always a good idea to take the time to remove all burrs from cut or machined metal. Most of these burrs are razor sharp and can cause serious cuts. It just seems that most people like to stick their fingers in things, especially children. The natural thing to do when encountering one of these burs unexpectedly is to jerk your hand back which can cause more injury. Removing them can also eliminate injury while handling the material later.
A file, de-burring tool and grinder are excellent for this purpose.