Robo Rainbow graffiti machine

[mudlevel] built this rainbow graffiti producing robot for an art exhibit in San Diego. While there are no build details we can easily pick this apart from the pictures. Looks like the brains are an arduino, the drive is a power drill with the trigger removed, and a few other servos for firing the spray cans.  The counter weighted arm for creating the rainbow was a pretty good idea too. Watching this, we had an idea for a super simple purely mechanical way to do this that would be similar to a catapult.  You could use the motion of the trailer to “wind up” the counter balance with a simple ratcheting spool of string attached to the axle. Engage your spray cans and let the balance drop and you’re done.  Pedal on to re-wind the counterbalance for another rainbow.

Man made rainbow uses ONLY sunlight and rainwater

This rainbow is and is not natural. It’s the product of rainwater and sunlight so in that respect it’s natural. But as you can see, it’s not raining. This is an art installation that uses captured rainwater, stored solar electricity, and irrigation equipment to float a heavy blanket of mist in the air. The prismatic effects of the suspended water particles separate the sunlight into various bands by wavelength and a rainbow springs into existence.

We’ve done this before with a garden hose in the back yard. It might be fun to try to build a version that recycles the water as this does, perhaps using a rain barrel as a reservoir. It would certainly be much easier than pulling off that water-based 3-D display we’ve been meaning to undertake.

[Thanks Xb0xGuru]