I have been saving my quilt scraps, even the tiniest bits of selvage and strips from between squares. I sorted the scraps into strips for weaving, and scraps for collage.
Some scraps can be made into strips by cutting in a zigzag.
You can make a loom for a child using a shoebox, a piece of corrugated cardboard, or an unused styrofoam meat tray. See Weaving with Children, one of my posts, for instructions.
I used packaging string as the warp, and to make a firm edge at the bottom. My warp strings are a quarter of an inch apart. The warp is just one long piece of string wrapped round and round the box, with the ends tied together. The upper primary children are going to weave next week using the looms I made them. I can't wait to see the results.