She Sells Seashells by the Seashore

I sure hope I have enough shells.....looks like a lot but it's a pretty large mirror. Large clam shells in lower left corner looks like steamed clams....yum...focus !  I went to the dollar store and found individual small baskets with shells...dollar each. I then found a couple of shell place matts from Goodwill that I took apart. Finally I have a bag of shells that I have been collecting from garage sales over the pass couple of years. I'm headed to craft store. I have a question about the longivity of glue sticks compared to any other kind of craft glue. I would hate to do all this work and than in a couple of years, gravity starts leaving shells on my floor....
Remember this project is trial and hopefully not error. Let's go...one petal at a time.