Gear has a 1:1 ratio. One turn inside will also turn the outside exactly one round.

Video: https://vimeo.com/456871494

Design:

• Fusion 360 -> Tools -> Add-ins -> Spur Gear
• Fusion 360 -> Solid -> Create -> FM Gears (Internal Gear)

Design Notes:

• FM Gear does not use any offset. To counter that I made the module slightly larger.
• Instead of using FM Gear you could also create a normal gear and use it to cut out the internal gear from a round solid. But don't use any Backlash for this one.

Wiki: https://en.wikipedia.org/wiki/Epicyclic_gearing
FM Gear: https://apps.autodesk.com/FUSION/en/Detail/Index?id=6294804001663532834

Print instructions

I used PETG since it sticks very well to the print bed. With PLA I have often problems if I have fine details in the first layer.