Summary

I liked the planetary gear arrangement by MechMac666, but felt a couple of things needed improvement.
One- I thought it was too big, so I reduced the overall size about 30% and,
Two- I wanted it motorized.
I used a 12V, geared, 10RPM, right angle motor drive unit similar to:
[https://www.amazon.com/dp/B099K6RW48?ref=ppx_yo2ov_dt_b_product_details&th=1].
The motor is mounted on the back, and I included a motor cover that also serves as a base for the whole thing. Didn't want to put up with a lot of support during printing, so the motor mount bosses are separate pieces that are mounted on the cover with screws, then glued onto the back of the base.
Since it took a bit of work to create the motor mount, I've included it for anyone to use to mount a similar motor on some other project. Just convert to "HOLE" and place appropriately.
Finally, the sun gear mount on the motor shaft is intentionally tight. If too tight on your printer, enlarge the hole by a 0.2mm step, but don't enlarge the whole sun gear; the clearances are rather tight.