I wrote about leftover needlework before, however I find the magic ball, a yarn skein from yarn rests knotted together, so great that I wanted to mention it again.
It doesn’t matter there whether you knit it or crochet it or both, it looks greatnearly every time. Some use it for freeform work, some crochet only half double crochets or knit in stockinette or garter stitch.
I think it would also look great if you used the magic ball for weaving.
Many people like the loose ends to be seen, in the instruction someone even suggested to add beads on the tails, which have to be long enogh for this (entry of mbriz).