This used to be an old, broken 3D printer. It was donated to MakerClub by the MME department, with the end goal of letting any club member use it as a CNC base for their projects.
To prepare the device for club use, I removed the broken heating element and replaced the microcontroller and motor drivers. The X, Y and Z axes are now controllable by sending commands from a laptop to an Arduino over serial.
As a case study for the club's prototyping workshop, I added two movement axes to the CNC and turned it into a watercolor painting robot. The rotation is controlled by a stepper motor, and the swing is controlled by a servo. I also built a new base out of laser-cut acrylic, and wrote a GUI for telling the robot what to draw.
I am currently working on improving the top section of the robot. In the new design, the brush is attached to the motor via a pair of header pins, so different sizes of brush can be used. Also, the servo motor has been mounted on a slip ring to allow for continuous rotation. The rotation servo motor drives the slip ring with a 1:2 gearing to allow for finer rotation.
The new mechanical assembly was designed using AutoCAD and OpenSCAD. All code and mechanical designs can be found at: https://github.com/Verkhovskaya/watercolor-robot