Modular Toy Robot Arm

[Following on from my first toy robot arm](https://www.thingiverse.com/thing:4555965)

This one is a bit more modular and can be used as a toy, desk lamp, microphone or camera stand via swappable add-on components. The gearbox code has also been fully reworked.

More components to come.

[Also on GitHub](https://github.com/tmackay/solid-core-compound-planet)

Print at 0.2mm layer height and ensure there is a 1-layer gap in the ring gears after slicing. Use a sharp edge to de-laminate the 1-layer gaps (listen for the "crack"). Turn the knob just a little to get the gears moving, working back and forth gently. A final tap with a rubber mallet should free everything up. Then apply petroleum jelly or lubricant of choice to gears.