This design was inspired by vintage ceramic Christmas tree lamps. You can customize the look with two styles of bulb, and any combination of bulb colors you like. There are a star and snowflake topper available, or you can just have a plain tree top. The default bulb profiles includes layouts with 2 colors of bulb and 4 colors of bulb combos. Note there are separate profiles for the two types of bulbs, due to the number of objects in each. Each includes both long and short bulbs of each color. The long bulbs are for the upper layers, the short ones for the two lowest layers. The trees I printed with Bambu Basic PLA. The bulbs are printed with Bambu Transparent PETG (except for the bright red which is Novamaker). Other transparent filaments should work as well. Normal PLA does not work well for the bulbs if you plan to put a light inside. It should work for an unlit decoration though. You can reduce infill on the bulbs if not making the tree as a lamp. 

When cutting the bulbs from the sprues, cut close to the bulb with the flat side of a flush cutter.

Due to the fairly low angle overhang, you may encounter some minor "zits" or strings on the underside of the lower levels of the tree. Dry your filament to minimize issues. Use a flush cutter to remove any strings, then a few quick passes with a kitchen butane torch can clean these up.

After inserting the bulbs and tree topper to your liking, assembly with the light module is as follows:
1) Thread the USB cable through the holes in the bottom of the bottom plate. Then press the light into the bottom plate. 
2) Insert the bottom plate into the base of the tree. 
3) Twist the bottom plate clockwise to secure.

Enjoy! I'm excited to see what color combos folks print!

Attribution: The base of the lamp is derived from the official Bambu Labs lamp model: https://makerworld.com/en/models/13717?from=search#profileId-13429