Doodlebots are simple to construct drawing robots that create random coloured patterns as they vibrate around on a sheet of paper. While we definately didn't invent them (the idea has been around since at least the 1950s), we did improve them.
When we originally saw them, the cup, pens, motor, battery and spinner made a great set of components to a build that is simple to start, but contains great scope for improvement. They are easy enough to build that once you can make one, you can teach people how to make them; but there are enough variables and possibilities in the design, that no two are quite the same!
When we originally used these on courses, all of the components were only stuck together with tape. While this sort of worked, the main cause of failure was the electrical connection between the battery and motor. And having the whole thing vibrate, didn't help this ad-hoc connection! We've added the a wired battery holder and soldered connections (with strain relief) to the motor, so every motor spins, as long as the battery is in place. And having the battery holder gives us a handy on-off switch too.
Each motor needs it's offset weight spinner to create the vibration. Ours are laser cut from 3mm acrylic with 5 holes in it. By changing the position of the motor, (or adding blue tack to the spinner) you can adjust from a fast, high frequency vibration when it's almost balanced, to a slower, lolloping, larger deflection pulses when it's most unbalanced. Spinners are accurately cut to make sure they give push-on, friction fit to the shaft, so no glue is needed, but they hold firm.
These kits are great for workshops. At just £3 per person — or less if you use scavenged materials in place of the cups — they're cheap enough that everyone can build their own, or take it home with them.
We're proud of our open source work, so we don't just sell you kits, all of the instructions that we use to build the kits are available here, but if you'd rather not get down to the batch building, soldering and glueing required, we do offer kits for your own workshops and events to buy in multiples of 30.