If you want to do some hand piecing during a flight, my suggestion would be to have all the pieces cut and "bagged" and organized inside another zip-lock bag with the sewing supplies.
As for a cutting tool for thread, tuck in a dental floss container and use the cutter on that to cut your thread. Or, you could get one of the "ring cutters" made by Clover, I believe. It's a finger ring that has a small cutting hook attached.
Another little trick to keeping all those pieces organized by shape / color is to stack them, and leaving a long tail of thread, put a needle and thread into the stack all the way to the bottom of the stack, bring the needle and thread back through the stack, through the top of the stack. Cut the thread, leaving another long tail. Take the threads on top of the stack and tie into a loose knot. Thus, you have all these neat and tidy "fabric stacks" that stay together in the bag.
When you're ready for any or all of the stacked fabric, just pull it out of the bag, untie the threads, and remove the piece you need from the top of the stack and the other pieces stay in place. If you haven't used the entire stack, you can just re-tie it and tuck it back into the bag.
This is a great thing to do if you want to take some piece work (machine or hand) with you on vacation. You would be amazed at how many projects you can tuck into your suitcase amongst all the other stuff.
Actually, I confess that when we go on vacation or just to the mountains for a few days, I have a separate small tote bag I use for stowing and carrying my "projects".
Finally, a major benefit of "sewing the stack" is that even if you're in your "quilting place" at home and you've done this with the pieces, should you bump one of the stacks amd they tumble to the floor, all the pieces will stay together.
Oh...almost forgot. My suggestion about "fabric stacks" works only if you're organized enough and plan ahead so that you've decided on pattern, fabric, and have thus actually cut the pieces BEFORE you're stuffing anything into a suitcase. :lol: I'll let you use your imagination as to what really happens...sub-set of stash, pattern, cutter, rulers...now you know why I need a separate tote bag! Busted! :wink: