WaterColorBot V2.0 comes assembled & tested.
Neither a toy nor a gadget, this WaterColorBot is an attractive educational project. Its purpose is to involve girls, kids, adults, and teachers into active robotics and creative making. It not only provides opportunities for young people to build and learn about computer numerical control and to learn how to program a robot. You'll use it far beyond that horizon. To start, the WaterColorBot V2.0 is essentially a specialized pen plotter with a sturdy wooden frame. It uses a set of watercolors to paintbrush your own digital artwork onto paper. It dips its brush in water, goes and gets the right color. The robot paints before your eyes, either reproducing a finished vector artwork from your computer or following along as you sketch in real time. Works with standard watercolor paints and paper (no specialized supplies required).

Compatible with any Mac, Windows or Linux system

The WaterColorBot is also a genuine computer-automated, numerically controlled machine (CNC) that lets creative people do amazing things.
Two motors built into the frame of the robot drive each a little CNC-machined aluminum winch. This arrangement pulls cords attached to rods that control the X and Y position of the brush, mounted on an aluminum carriage.
WaterColorBot V2.0 comes assembled, tested, and ready to use, with a starter set of watercolor paints, paper, and a brush. Other watercolors are supported. A library of supported paint sets is maintained as part of the documentation. Customized lower decks can widen the gamut of usable paints: liquid watercolors, tempera paints, and watercolor pencils.
You only need a free USB port on any Mac, Windows or Linux system, as well as internet access to download software, instructions, and drawings.

Formats and modes

Two different painting modes are available: "Automatic" painting mode with various interval settings for re-wetting the brush, and real-time sketching in "manual" painting mode, following a sketch on the screen, and manual commands for re-wetting the brush.
For the vector artwork, the robot uses the SVG file format. The well-known Inkscape software can convert to SVG from many different file formats (PDF, Illustrator, ...). For experimenting with pixel-oriented image and converting these files to color vector artwork, one should preferably use other software conversion tools.

Laboratory for Science, Technology, Engineering, Art, and Mathematics (STEAM)

WaterColorBot is a  well-documented fully open-source project (hardware, firmware, and software).  Its hackable hardware was designed to be extended and repurposed for many other subjects far beyond the horizon of the drawing/painting bot.
It also is a laboratory for teaching and learning topics and principles within the Science, Technology, Engineering, Art, and Mathematics (STEAM) umbrella.
Physics: Additive and subtractive colors, surface tension, thermal conductivity, pulleys, winches, force diagrams, tension, friction, torque and force, electrical power, strength of materials, flexibility of materials, elasticity.
Chemistry: Solubility, evaporation, chromatography.
Biology: Sample preparation, using the WaterColorBot to paint bacteria onto agar or using the WaterColorBot as a pipettor. Painting moss spores onto surfaces for growth. Painting chemical inhibitors for culture growth.
Technology & engineering: Lithography (using an etch-resist pen). Printed electronics, using a conductive pen to create circuits. Introducing students to design software, CAD, and numerical control concepts.
Mechanics: Motion control, power transmission, DC and stepper motors, linear translation mechanisms, rotary translation.
Electronics: Circuit design, microcontrollers, power supplies, voltage regulators, digital logic interfaces, H-bridges and motor control.
Software: Computer graphics. Numerical control. Firmware design.
Art: Make paintings, and explore other media (oil paints or pastels).
Mathematics: Paint tangrams and cut them out. Prove the Pythagorean theorem. Geometric constructions. Graphing functions and data. Coordinate systems.