Designed this gyro keychain in Inventor as a gift for my friends. The keychain prints in one piece, and consists of three rings encircling a center hub. The rings are 3mm thick and spaced 0.6mm apart. The center hub has been left unadorned in the provided model, but I suggest embossing a name or symbol onto it for a personal touch. If you print multiple copies of this gyro in different colours, you may also extract the planetary rings and interchange them for unique colour combinations!
Supports are only needed for the keyring attachment.
The gyro should spin nicely without any post-print work. If you have imperfections within the rings, knock them off with a blade or sandpaper, or spin the affected rings by hand for a few minutes to smoothen them out.
This gyro underwent several iterations in order to find a good spacing that allowed the rings to spin without being too loose. The rings are angled such that they do not freely pop out, but I found that an angle steep enough to completely prevent the ability to extract the rings unfortunately also prevented the rings from being able to gyrate.