Going along with the picture frame craft idea, you could also get those little containers filled with stick on jewels/gems, or foam hearts, flowers, butterflies, etc. You just peel the backing off and stick it all over the frame (about $1 for a wooden one). You can find all of these things at a craft store. Then the project becomes totally child made.
I do have to admit though, I like the idea of hair clips and headbands, but you do have to be very careful about kids not getting burned with the glue gun. There is always the option of you doing it at a table, and each girl coming to you one by one to have their flowers glued on. But then you are doing the craft, and not really them.
Mama to "The Fantastic Four":
DS 02
DD 06
DS 09
DD 12