Apparently I didn’t write this one up already. Here’s a build from a couple of years ago:
It’s a coffee table with a bed of sand, and underneath is a CNC plaform and a powerful magnet to drag around a stylus and make patterns.
The hardware is pretty straight forward. I bought a coffee table from Ikea and mounted a wooden frame underneath:
Then mounted the CNC gantry under that:
I spent a while troubleshooting the motion. Nick and I both made tables previously, and the secret seemed to be having a soft base underneath the sand, and also using a cylindrical disc magnet rather than a ball.
This is to minimize the amount of ‘uphill’ work the magnet has to do. A cylinder is just dragged through the sand horzontally, whereas a sphere tends to jump and skitter irregularly, which is bad for both the smoothness of the pattern, and how pleasing the sound is to hear.
It has a glass top, but we removed it some of the photos.
Here’s it in the Powerhouse Museum, briefly brought in for a photoshoot before Maker Faire a couple of years ago. That’s right, something I made belongs in a museum 😀
Edit: As requested, here’s the processing code used to make the patterns. It was very quick and dirty but might serve as a starting point: