I've always been a big fan of K'nex, ever since I was a little kid. Then, when I discovered this website, I felt like I had hit the jackpot. This is a "robot" that I built out of knex, it's designed to play the piano. This version can play up to a 16 note sequence in a 12 note range. I call it "Zeeanobot" (Zach's Piano Robot), corny, I know, but I couldn't think of a better name. I spent a lot of time on this, and I'm very proud of it, so please be nice. Just to be clear, I have not tried it on a real piano, I built it to play my Yamaha DGX-230. You may need to modify the design slightly to get it to work on real pianos or other keyboards.
Please note that this is my first real instructable, so I'd appreciate any constructive criticism. Thanks. (So far the response has been mostly positive, so thanks everybody! I put a lot of work into designing and building this so I'm very proud of it. I'm glad you like it too.)
The first video is a mechanical view of Zeeanobot, showing how it works.
The second video is Zeeanobot playing a simple proof of concept song.
The third video is a duet of Katy Perry's "Hot and Cold". Ignore the errors on my part, they're not the point.