The ultimate gear sphere: 32 gears (3 types), small scale, etc. Unfortunately, you also need 32 pieces of M3x10 hex key screws as well. Here is a video.
Print the core, 12 pieces of gear A and B while 8 pieces of gear C. If you want to use 2 M6 hex keys to rotate (see video), print 2 pieces of gear A_hex6 and 10 of gear A, instead. Use the M3x10 screws to mount the gears to the core.
The core is a partially truncated version of the dual of the truncated octahedron. The dual of the truncated octahedron is also known as tetrakis hexahedron. The core has 24 not-so-regular pentagonal faces and 8 regular hexagonal faces. Mount gears A and B to the not-so-regular pentagonal faces accordingly, then gears C to the hexagonal faces. Gear A has 27, gear B has 18 while gear C has 21 teeth.