the unfortunate thing (that I have learned to my regret) is that certain things are not allowed in carry-ons and will be confiscated anyway. and you *have* to check them. any useful tools for example. I've nearly had pliers and screwdrivers confiscated, (and that was before 9/11.)
one entertaining example (from 2004) was the day I traveled with a devil stick, (juggling toy,) that looks a bit like a disassembled pool cue. at the checkpoint they asked me if it was a pool cue, I said no and they said okay, but if it were a pool cue they would have had to confiscate it.
now mind you it looked just like a pool cue, weighed about the same as a pool cue, made out of similar wood to a pool cue, but because it wasn't actually a pool cue, they didn't have to confiscate it. if it had been in checked baggage, it wouldn't have been an issue. but it probably would have broken.
due to traveling with some odd juggling toys on a semi regular basis, I have taken to writing long, detailed notes to the TSA, explaining what all my props are and leaving it in the suitcase with the props. I have never failed to get a 'your bag has been searched note' and I haven't lost anything, (yet.) incredible pain in the ass.
on the other hand, I was once driving back into the US from Canada, where I had bought a flute to play. (normal metal type of flute.) and I nearly got penalized and the flute confiscated for not declaring the flute as a 'commercial object'. oddly, they said nothing about the 10 packs of peanuts that it was sitting on when they found it searching my car. I'm beginning to think Customs just has a thing for flutes...