This is my first model and it worked out quite nicely. The candle will have 76mm diameter.
You will need 4 bolts, atleast 100mm long. I am using 10mm bolds 100mm long.
I printed it with eSun PLA+ and it whitstood the candle wax heat good. Before making the candle I applied some grease on the inner walls. Then I waited until the wax was about 60°C and poured it in. When the wax has cooled inside the mold you may need to pour some more wax on top.
If I ever need to make another one, I will add some slots to the sides where I can pry it open more easily with screwdriver. …or you can print this remix from Biffiest: https://www.printables.com/model/222786-sphere-candle-mold-with-opening-tabs-remix
The author hasn't provided the model origin yet.