“By attaching a string to two small electric motors rotating in the same direction, you can create and play with a special class of waves called standing waves.”
I finally got around to making this!
The core build instructions are here. They have some really great projects.
My variations
21.6mm pipe instead of 0.5inch - I had the pipe, and it meant that I didn’t need to cut the elbow to hold the motor. I held the motors in place with a bit of dowel.
5V USB power supply instead of D Cell batteries
PWM motor speed controller instead of a potentiometer. I hot-glued the speed controller to the pipe rather than using a wooden board.
I ran the wires through the pipes to make the build neater
I added some non-slip foam pads to the underside to reduce vibration noise transmitting to the table.
By twisting the pipes, I can fold it flat for storage.
This is one of those projects where the fun is in the build plus the next 10 minutes of play, so I have no further use for it. If anyone would like to borrow it, let me know.