The Spherebot is an open source machine capable of printing designs onto spherical objects, such as Xmas baubles!
The Spherebot features two stepper motors, one servo motor for marker actuation, some cheap mounting hardware, and a whole bunch of 3D printed parts—all of which are available on Thingiverse. In this design they used a 3D printer controller board called the 3Drag by Open-Electronics, which is based on the ATmega2560 (the same microcontroller as the Arduino MEGA). The Spherebot doesn’t require all three axes or an extruder, so they only installed 2 out of the 4 stepper drivers on the board to save cost.
Once you have it all built, it’s a simple matter of uploading your design into the free Spherebot-Host-GUI provided on GitHub. Stick around after the break to see just what it is capable of!