Programmable beat machine without electronics

You just composed a world hit, but you cant play it because the drummer probably has his holidays. Don't try to find him and 3D print a replacement instead. Two drum sticks are operated by two wheels with a number of teeth, up to your choice. By printing alternative wheels, you can program the beat. Two wheels are added as an STL file. An OpenSCAD file is included, so you can easily print your own wheels. By changing the voltage over the miniature geared DC motor, the frequency is changed.
https://youtu.be/ecxUzuLXm4E