Solid Core Compound Planetary Gearbox (customizable)

https://www.youtube.com/watch?v=_fb97PWaaFY

To follow on from previous designs, if we target less extreme gear ratios we have more room to move with our choice of gears. In particular, it would be most beneficial to have fused sun gears in both stages. This would allow for the drive force to be distributed over a larger contact surface, assist in initial post print processing and improve efficiency.

A fused sun gear introduces a constraint that the sun gear teeth is a multiple of the corresponding planet gear teeth, so that it is in effect a mirror of the planet gears and the two stages turn in unison with the planets in a 1:1 ratio. Even with this constraint, some absurd gear ratios are still possible (up to 616:1 within the range of gears specified in this customizer) but around 50:1 to 100:1 seems a good target based on existing designs.

Incorporating 3-layered approach from https://www.thingiverse.com/thing:3210223 and https://www.thingiverse.com/Gear_Down_For_What/about t