Modified Gear Ornament, altered to make it easy to insert string light bulbs to make the lighting more interesting.
Once built, if there is a web in the square, carefully use a knife to make diagonal cuts inside the square, from corner to opposite corner. Most tree lights should be able to gently push in to light up the ornament from the inside.
Vase mode, with 2 bottom layers. I used 3DXTech's clear ABS. I used a 0.6mm nozzle, slicer set to make a 0.72mm wide bead width. 0.5mm layer height might be worth trying too. 0.4mm gives good results too. For 0.4mm nozzles, try 0.3mm layers.
I took the Gear Ornament and added a square hole in the bottom to contain any fracture spreading. I also tapered the base more so it looked better for this task. I used TinkerCAD because it was quick to learn.