If the girls will continue with sewing, a cupcake pincushion would be appropriate; not sure where I saw the pattern, but I know it's out there(the teacup idea is also cute).
The recycled denim idea is also very good. Use it up, wear it out, make it do or do without, as they say.
Good luck, have fun! Hopefully they will be able to finish their projects completely, and won't be stuck with UFO's.