This model includes a coil that wraps around the top branch of your Christmas tree, and a star that can be modified to fit your needs. I printed the coil with .2mm layer height and 6 perimeters to make sure it is solid. The star was printed at .3mm layer height with 2 perimeters and 10% infill. Both parts can be printed without supports. Once the parts have been printed, a bit of super glue will help hold them together.

I have included STL files for stars with a 250mm or 200mm diameter. The printed model in the photos is the 250mm star. If you want to modify the native CAD file, you can use OnShape Free and modify the file at this link.