This is an improved version of harvdog92's threaded remix of Lalala65765's Dragon Egg box Chi. I've added a chamfer to the inside lip to allow for printing without supports.

Print both parts right side up, in other words, the bottom threads up and the top threads down. You may want a brim around the bottom, it has a low contact area and Ive knocked a couple loose during printing.

Print Settings

Rafts:

Doesn't Matter

Supports: