To start with, this is the link to my latest project. It's 7.2:1 reducer for robot drive systems that fits any Ampflow 3" motor. The inspiration is from the Team Whyachi M3 gearbox which is made out of carved out solid aluminum billet whereas my concept is made out of segmented parts to lower the processing cost. I haven't made one yet but hopefully could get to finish one within the year to test it out.
https://grabcad.com/library/gear-box-for-combat-robots-1