Second design to try is a "simple" spur gear box. This will be based on a simple Boxes.py box based on finger joints. There already exists a generator on Boxes.py for quite a while. But it is even further from being usable that the planetary gear box. What's wrong with it basically translates one to one into the projects design goals...

First scribbling on paper suggests that it will be difficult to come up with one universal design. So this will probably end up as several different generators each for the number of stages from one to probably 4. This should cover the range from 2:1 to 1000:1.

I am still at beginning with this design. One thing I want to try is having a hex bolt in the last gear and also fit a ball bearing within the same gear in another layer. This should allow supporting the output shaft on the bottom side and so having the full height of the gear box as support (with a second bearing on the top end).

It very clear that the gears need different strength and though thickness for the different stages. Need to check out if I can automatically adjust the modulus of the gears. May be squeezing even bigger reduction out of the earlier gears. Lots of stuff to try out...