A spiral design, created in FreeCAD using the Curves workbench and mainly the Sketch on Surface and Gordon Surface feature. Fits a 90cm high tree very nicely.

Printed in PETG (because I had no PLA in that color) with 0.1mm layer height, spiral vase, no bottom layers, no top layers, brim (because I'm a sissy). The top part turned out not as well as the rest, maybe you can fuss around with the print settings to increase cooling for the last layers or slow down the print… idk.