How about giving your kids some hama (perler) beads and teaching them how to make a free form hama bead cloud and raindrops mobile? This project does require an iron, so adult or young adult supervision is required, but the results are truly wonderful, and the few minutes that you'll need to help with the ironing is surely worth it! For detailed instructions and even a template, check out the post that inspired us over at my poppet.
Abstract shapes can't really be made on a hama bead form, so one just arranges the beads on a sheet of baking paper in the desired shape and then places another sheet of baking paper on top and gently presses down with the iron to melt the beads and adhere them in a clump. Of course a template is a good idea, and one can also trim the shapes with scissors afterwards, which we did not do.
Holes can be made while the shapes are still hot, using a large needle. And that is it! Hang your raindrops from your cloud, (I'd suggest making many more than my daughter did) using fishing line or thread, and a fabulous little mobile will grace your home this spring!