A couple of Interesting Mechanisms

PART1 : oval gears

radius keeps changing as it rotates so you get variable speed from a constant input. conjugate pair has to be derived numerically, learned that the hard way with the gaps.

PART 2 : crossed helical gears

also for skewed shafts but using standard helical geometry. contact is point contact so lower load capacity, but simpler to make. worm gears are the extreme version of this.

PART3 : hyperboloidal gears

for shafts that are skewed, not intersecting and not parallel. the gear body follows a hyperboloid surface which is what allows contact across that skewed geometry, basically bevel gears but for skewed axes.

ASSEMBLY INSTRUCTIONS : just slot the gears in their places as shown in my journals, thats all.

#10% infill recommended