Here's a fun mini ball that works at the top of large trees or anywhere on a small tree. You can scale it up as much as you want. There's a lot of detail in the model.

Not for commercial use. Please see license agreement.

I printed the main ball upside down so it would get good bed adhesion. I've since printed similar ornaments right side up and they worked well, too. I recommend using grid supports for the ball and 1 perimeter to keep it light.

You'll need some infill for the ball, but not much. I only added 2 layers of infill just above where two arms meet. I used rectilinear infill at 30% I've included my PrusaSlicer 3mf files and GCODE for my Prusa MK3S+, which takes a lot of the work out for you. I know you can do the same thing with Cura. If you use a different slicer that doesn't let you add infill in only certain places, check to see which would add more weight - infill everywhere or adding enough perimeters to not need the infill. You probably only need 2 perimeters total and a decent top/bottom setting to avoid infill.

I printed the cap right side up with 2 perimeters and organic supports.