A small air pipe. Blowing to keep suspended the sphere. Who lasts longer?
The pipe is simple to print: use a raft and no support. Infill 20%, 3 shells.
The sphere is hard to print. I tried to print it in a one shot. I finally split into two half spheres which I then glued together. Semi-sphere parameter: infill 20%, 3 shells, internal + external support, raft.