This is a worm gearbox rotator thing with integrated BB ball bearings for making antenna rotators for light weight antennas. The design is based on the "Almostly customizable BB bearing generator" by Hoshiimiki: https://www.thingiverse.com/thing:3177466
The gears are made with the "Helical Gear Plus" free Fusion 360 plugin by Ortus Lab:
https://apps.autodesk.com/FUSION/en/Detail/Index?id=1259509007239787473&os=Win64&appLang=en

ID: 40.4mm (the 0.4mm is for tolerance)
OD: 65mm
Gear ratio: 40:1

Requires a lot of 6mm PLA BB ball, a nema17 motor, 3xM3 16mm screws and some super glue.
Fusion 360 design files are included if you want to customize ex. the motor holder.

There are also stls&f3d file for a EM-462 stepper motor that i scrapped from an old Epson ink jet printer.

Assembly:

1. Print the rotator_outer and rotator_inner parts
2. Put it together and fill it with the BB balls, make sure to leave one ball out for smoth operation
3. Rotate the inner part of the rotator with your hand until the binding is minimal
4. Print the rotator_worm_shaft horizontally, remove support and sand lightly with sandpaper.
5. Print the rotator_motor_holder and glue it to the gerbox with super glue. There is also a hole for a M3 screw but i only used this for alignment.
6. Put the rotator_worm_shaft to the nema17 motor, put the motor on the assembly and check how it fits
7. Glue the rotator_worm_shaft to the nema17 output shaft
8. Fasten the nema17 motor to the assembly with 3xM3 16mm screws
9. Run the rotator for about an hour to wear in the 3d printed parts
10. Add silicone grease for lubrication