A lot depends on the airport, the country and the individual security agent. I wouldn't chance scissors of any sort and just take a container of dental floss and use that for cutting. (plus you can clean your teeth!) They do sell little round thread cutters, but a floss container is just as effective, less expensive and serves a dual purpose! As for needles - you might want to check with the airline, but you could just slip a couple into a little case like Terri mentioned and see what happens. The worst case scenario is that they confiscate them. So bring a book - just in case! Many of them now allow knitting needles, but a few don't. My friend was told she could bring plastic knitting needles, not metal, but I was never told that. Most allow crochet hooks, but I had a problem, not with security - they let me through with no problem, but with a flight attendent on Quantas. She got all crazy and actually had the co-pilot come to my seat and ask me to put it away for the rest of the flight.