I have uploaded two versions of my atom pendant. The first is all in one piece, lots of infill to clean away. The second is much easier to print, hardly any infill to clean away, it just needs to be assembled once printed. The center has holes that will hold all of the other pieces in place, but I recommend a dab of glue at each meeting spot for extra strength.
For the other, all-in-one version check out : https://www.vectary.com/u/naomi.kendall/atom-jewellery.-science-geek-gift.-pendant-necklace