This is  a tiny cycloidal drive designed to fit a NEMA17 stepper motor

Reduction: 19:1

The cycloidal ring has been designed to be interchangeable, so if you want to fit a higher/lower ratio cycloidal setup, you only have to print the disk and the outer ring. 

Print Details:

Material - PLA

Weight - 22.19 g

Supports - Yes

Print Time - 51 minutes 55 seconds (on Creality K1C printer)

Extra Hardware Needed:

2 x Bearings - 6800-2RS (One for the cycloidal disk and one for the output shaft)

4 x M3 screws (25mm length) … can be shorter if you dont user the spacer