I spent a lot of time designing, manufacturing and verifying the cycloidal extruder. This is the V0.1 version. I have installed this cycloidal extruder on my ender3 and tested it. It is feasible.

Video(make): https://youtu.be/mzItrep52yQ

detailed steps: https://www.instructables.com/Build-a-Complete-Cycloidal-Extruder-for-3D-Printer/

Note: you must pay attention to the direction of the cycloidal disc assembly, otherwise it cannot be assembled, please follow the video prompts.

In order to focus more on this extruder, I have created a fb group for everyone to share and discuss: https://www.facebook.com/groups/3202068370116874/?notif_id=1651486339049109&notif_t=group_milestone&ref=notif

BOM: please check out the file: cycloidal extruder non-printable parts-BOM