Hi Jen!
Cool! I'm gonna jump right in here.. after all, it is one of my favorite topics!
Yes, you can add cosmetic glitter right to your recipe.
You can use just about anything for a mold, but I think those plastic ornament balls are easiest. You can get them at JoAnn Fabrics or any craft store. Each girl would need 1/2 of one to use. They should definitely be hard enough for the girls to take home. If they end up crumbly, which would be if you didn't get quite the right balance of dry/wet ingredients, you can always put them in bags and use them as magic bath rocks or something.
Lip Balm- would go great in those little flower lip pots.
If you were motivated, you could do some melt and pour soap with glitter, too, or with cool little rings or whatever.
I think that covers it, but if you have more questions just yell.
Tami
www.soapbytami.com
edited to add--
You could do solid perfume, too, if you wanted to! It's the same process as lip balm.