If you do want to try making music on your Makerbuino, I made a prototype music tracker that I posted here. I never finished it, because I was trying to add the ability to save to the SD card and it got frustrating, but songs you make can be exported to play in a game. It’s just a little complicated to do.
If you want to try it out I can answer questions about it. I stopped working on it because I felt like it was a lot of work for something that nobody would use, so let me know if you find it useful or interesting.
Edit: the video of the tracker in action is a bit out of date, so the most recent version has a few more features and changes, and there is a way to set the BPM.