This is a helical gearbox, which transfers torque between offset axles at a right angle.  It is comprised of 2 identical helical gears, 2 axle/handles, 2 casing halves, and 2 casing caps.  The axles are designed to be a loose fit/press fit inside the gears(0.5 mm clearance), the caps to be press fit around the casings (0.2 mm clearance), and all other parts to be loose fit.  To create a tight fit on the axles or on the end caps, scotch tape or similar tape may be used to reduce clearance.  The gear bores are designed to be 1/2" hex.   All parts can print perfectly without support.

Shown parts were printed with a 0.7 mm nozzle with a 0.4 mm layer height in Solutech Gold PLA.  The caps were press fit, but the axles did require scotch tape to stay seated in the gears.