I made a tiny key necklace for my girlfriend, I first had it made from plastic. Now I would like to go with one of the silver or brass options and I would like to add a Black Pearl to the top of the crown piece. However, I believe I must create the prongs to hold the pearl in place. My question is, what are the design constraints when designing the prongs? I imagine that the thickness would likely be less than the required wall thickness. I'm not sure how to design these prongs and what my approach should be. Thank you.