Blot

Blot

Blot is Hack Club's drawing machine project — build a pen plotter that draws your code.

Projects Hardware

Blot

Blot is Hack Club’s pen plotter project. Like Sprig, it’s a “You Ship, We Ship” project: write a drawing program, get a free Blot kit.

What is Blot?

Blot is a two-axis drawing machine (pen plotter) designed by Hack Club. You write code that moves the pen, and the machine draws it on paper.

How It Works

  1. Go to blot.hackclub.com
  2. Write a JavaScript program using the Blot API
  3. Preview your drawing in the browser
  4. Submit to the Blot gallery
  5. HQ ships you a Blot kit to assemble and run your drawing

The Blot API

Blot uses a simple JavaScript API for turtle-style drawing:

const t = createTurtle();

// Draw a spiral
for (let i = 0; i < 100; i++) {
  t.forward(i * 0.5);
  t.right(91);
}

drawTurtles(t);

More complex drawings use parametric equations, fractals, L-systems, and more.

The Hardware

The Blot kit is a CNC pen plotter with:

  • Stepper motors on X and Y axes
  • 3D-printed frame (all files open source)
  • Arduino-compatible controller
  • Servo for pen up/down

Assembly takes about 2–3 hours. Full instructions are in the repo.

Browse hundreds of community-made Blot drawings at blot.hackclub.com. From geometric patterns to portraits to algorithmic art.

Tips

  • Start simple — a basic geometric pattern is a great first submission
  • Iterate in the browser preview before building
  • Look at existing gallery submissions for inspiration
  • Comment your code so others can learn from it