Just as an addition to @shauki 's post with the 3D printed robotic arm that had a low parts count, I met a guy who was featured on hackaday recently maxing out a 1000lb scale with 3D printed gears.
Along with that project, and his ratcheting CVT, he had this really cool arm that had its own gearing and super low hardware parts count. (Project is almost 100% 3d printed pieces)
The cool thing about this is that you don’t really print any big pieces. The thing is completely modular, even down to the gearboxes that you print. That’s why I’m linking the collection for this arm. It’s not all in a single Thingiverse project file.
https://www.thingiverse.com/Gear_Down_For_What/collections/robotic-arm