Using lithophanemaker.com, the Lithophane sphere maker to make Christmas bulbs is amazing! However, I didn't like the available attaching options for hanging the bulbs, such as the bulb clips. They just didn't attach or hang on a tree secure enough to my liking. I designed this bulb insert and threaded topper to easily hang a bulb directly on Christmas tree lights. Below are simplified instructions on how I print the threaded insert directly into my bulbs. With a small raft, I have been printing these with no supports.

1. Key settings in lithophanemaker.com's sphere maker when generating Lithophane bulbs. Set Cylinder Outer Diameter (mm) [set to 0 for no cylinder]: to 0 and Top Hole Outer Diameter (mm) [set 0 for no top hole]: to 13mm.

2. Using your 3D Printing Slicer, align the threaded insert to your lithophane bulb opening and merge/group the objects (images attached are from Simplified3D, but Cura and other slicers have same features). I prefer printing models outside-in and have had no issues with lid screwing onto threaded inserts.