I found my first attempt pretty good, although it had some things that bothered me, so i made a new and better one :)

Improved from my first design:

• using truer hypocycloidal gears instead of cycloidal gears.
• added chamfers to reduce elephant footing and smoothing the parts for easier assembly.
• added external ridges for tighter lids and better grip.
• increased internal tolerances for better fluidity and lower friction.
• Better backdriveability
• also as a side effect made it much smaller without reducing strength and resistance.

You probably don't need help for assembling cuz it's pretty simple, but for consistency, 

for assembly:

• the cycloids needs:
•    -to fit the output shaft: have a 90° offset, so that the valleys of one matches the peaks of the other, and the holes are aligned
•    -to fit the eccentric crank shaft, slightly shift them until it fits the crank shaft
• then put the whole thing in the outer cycloid
• then close it with both lids

You can also assemble it by closing the outer cycloid with a lid, placing the output shaft in, then a cycloid, then the internal part of the eccentric shaft, then the other cycloid, then the external part of the shaft, and finish it off by closing with the other lid, but this requires some knowledge about cycloidal drives.