DIY Robot Joint 3 and 4 with Cycloidal Actuators - 3D Printed Prototype

Ordered a ton of aluminum, CNC tools and hardware. The Teensy 4.1 board controlling the stepper motors has also arrived. Within a short period of time we will get the robot all out of aluminum from J1-J4. What do you think about continuing with 3d Printed plastic from there for the complex wrist? So basically a hybrid robot. Plastic parts could be reinforced with metal or carbon fiber?
This video shows the elbow joint with two cycloidal drives, entirely made from 3D-printed parts! One driver and stepper motor is still missing, sorry! This prototype helps me test the design before machining it from aluminum.