I am very pleased to report that my beaded beads keep their shape with additional beads! In fact, I think I like them even better. I had started out designing around a triangle base, as that is a very sturdy structure; I was concerned that they would fall apart if I stepped away from the triangle, but they didn't! So I guess I'm a better engineer than I thought; or just plain lucky.
I'm still searching the web, trying to see if anyone has beat me to this design. So far, it's looking good; I haven't seen anything like them yet. But I'm still looking.