Don't pay $65 a set from Amazon or grainger.
For sale is one set of BOSTON GEAR WORKS spiral miter gears.
3/8" BORE AND 3/32" Keyway
These gears are beveled at a 45° angle so they mate at a 90° angle. These mesh together and turn very smoothly because of the spiral design.
Use your imagination and use these for whatever you want. RUBE GOLDBERG , ROBOTS , TINKER, STEAMPUNK ETC.
If you pay before noon Eastern time I will mail these the very same day.