Got a Kiwi Co. box with my little sister and decided to copy the tool they provide for creating spool knit animals. Good CAD exercise and probably has some use as a test print for thread tolerances and small detail strength - need good layer adhesion for the little arms to not break.

The design features two different size rings for making various sized knits. I also included a slit on the outside of each post which was present on the original model - this is meant to help guide the needle used to close the knit

Aside from this tool itself you only need thread and a plastic needle (which im sure could also be printed) to start using it! If you'd like to put your machine to the test and have something somewhat useful in the end give this design a shot! For tutorials look up how to spool knit.