Open Spiral Christmas Ball 2025

This is a fun and incredibly lightweight ornament that scales up and down beautifully. It's been printed as small as 25% and as large as 200%.

I've provided my PrusaSlicer project file and GCODE for a Prusa MK3S+ printer at 100% scale. I've also provided a project file with the ornament scaled up to 150%, 175%, and 200%.

Yes, you need supports - and not just at the base. You need at least 1 row of supports for the arms halfway up (I used 2 rows) to keep the arms from breaking as they print. Once they merge at the top, they are strong. Until then, they are weak and the taller they get, the weaker they get. Just use paint-on organic supports like I show in the screenshot. You also need supports for the roof of the ball. Supports for the loop are optional, but they help. The supports release effortlessly when I print with them and help guarantee a good print.

Use the Classic perimeter generator. I used 1 perimeter, no infill, and top and bottom set to 3. Then, I used height range modifiers to add an extra perimeter, 25% lightning infill, and top/bottom to 4 for 0-7.55mm. I also added an extra perimeter, 20% lightning infill, and top/bottom to 4 for 67.3 - 79.2mm. Above that, no infill with top/bottom set to 6. I usually print external perimeters first.