I guess that would depend on how much needs to go in it. For just the hand-sewing tools, I use a little plastic box that DD was given with nail polish, etc. in several Christmases ago. It looks like a little trunk, about 6" square, 4" high, with a handle on top. It's clear and sparkles (just a little bonus, lol!) and best of all the lid stays open without tipping the box over.
For bigger projects I have several plastic baskets I picked up at the dollar store a couple years ago, each about the size of a dishpan or small kitty litter pan. They hold scissors, thread, other tools, as well as the blocks/top or whatever I'm working on. I carry these down to the family room when I have handwork to do so I can sit with DH and watch the game or whatever with him as I work. I love these because they hold a lot, but they stack neatly together when not in use.