We didn't have any bangles that we could use, so we improvised. I hunted through our recycling pile and found some empty, clean kids yogurt tubs and worked out that if I cut the top and bottom off they would be perfect for the job.
I gathered my supplies: a ball of wool (I used a ball of multi-coloured wool, but you could use a solid colour or a few different colours), some scissors, sticky tape and the cut-down yogurt tub.
I started by sticky taping the end of the wool to the inside of the bangle, and then my little munchkin wrapped the wool around the bangle. I held the wool that she had wrapped so that it stayed taut and we kept going (and going) until we got all the way back to the start.
If you run out of wool part way, or want to change colours, to attach a new piece just tie the two pieces together so that the knot sits at the back of the bangle and then keep wrapping. As you wrap the wool, tuck the tails under the wool so that you can't see them.
When you get back to the start, tie the end of the wool into the first string and tuck the ends in under the wool so they don't stick out.
If you want, you can decorate the bangle with glitter glue, gems, etc. Or just leave it as is.