The Microbot Fidget is based on Hiro's Microbot from Big Hero 6
Both the parts snap fit together.
Print details:
Tested it at 50% scale too and works fine. Scalability should not be an issue.
The model has been designed to have a satisfying tactile snap at 90 degrees angles.
Note:
There are 2 files for the socket joint part, print the recommended version and stick both halves using some superglue.
I haven't printed the alt version as I feel that there's a high chance of the part breaking (layer separation)