With this pocket-sized drum, you can release your inner Buddy Rich while keeping your fingers busy. It is surprisingly loud. 

Printing
The ThumbDrum-skin-drum.STL file contains 2 separate parts: the drum skin and the drum body. If you want to print both with a single color, just print normally and both parts will print fused together. However, you can also use the print-on-print multicolor technique by loading the file in your slicer and then separating the parts. First print the skin in one color, and without removing it from the bed, print the body in another color. Use a 0.2mm layer thickness so that the drum skin comes out exactly 2 layers thick.  Also print 2 of the drumstick pieces and 2 of the fulcrum pieces.

Assembly
First, slide the little fulcrum piece over the thumb lever part of the drumstick as shown in the last photo. This will both push the end of the drumstick closer to the head, and it keeps the lever from bouncing around after each drumbeat. Next, clip each drumstick into the brackets on the side of the drum.

Playing
Grasp the curved finger notches between your index and middle fingers. Use your thumbnail to flick the end of the drumstick with a quick release. Try attacking the lever with your thumbnail at different angles to get more control of the intensity of your beats.

And now, a drum solo by the world's most rhythmically challenged engineer: