As of April 2018, the Travel Security Association (TSA) allows many sewing-related items in carry-on luggage. Ultimately, TSA agents have the final say in what can be carried onto a plane, so it is a good idea to travel with cheaper notions in case you have to part with them.
Some airports have mail service, so you can also bring a padded envelope and stamps in your carry-on luggage in order to mail back any items that are not allowed through security (you will need to step out of line, so be sure to plan enough time for this).
- Scissors under 4"
- Sewing needles
- Nail clippers (can be used to cut threads)
- Knitting needles
- Crochet hooks
- Scissors over 4"
- Rotary cutter
- Circular thread cutter (and other items with blades)