A guitar has 6 strings. When playing finger-style, you use your thumb (1) for the thickest 3 strings, and the next three fingers (2=index, 3=middle, 4=ring) for picking the next three, thinner strings. When picking the strings with a guitar pick, or plectrum, (which produces much clearer sounds), you hold the pick between your thumb and your index, so your index finger becomes unavailable for finger-style playing.
The thumbpick is basicly a pick that you can wear on your thumb, like a ring. It's a great invention, since it allows you to play both styles at the same time, giving you more creative freedom.
Because I didn't find one at my local music store, I thought why not make one myself back home? So, after playing with paper templates, I came up with a final vector template which, when cut out of a piece of plastic and properly assembled, works out just fine. I attached the vector template in the tutorial, either for printing and cutting the shape out with scissors and an xacto knife, or for CNC laser cutting.
1. CD case cover - I found out this plastic has many desirable qualities: ideal thickness, plasticity and elasticity. plus, it's nicer when transparent ;)
2a. For printing-cutting: printer, scissors, xacto knife/cutter, scotch tape
2b. For CNC: well, a CNC laser cutter
Since I don't have (yet) a CNC machine, I will take you through the steps I took: printing and cutting out.
Step 1: Print and Fit the Template to the Plastic
Open up whatever file format you can use from the ones supplied at the end of the instructable, and print it - just keep in mind that it should be printed at 100% scale. Then cut it roughly around and stick it with scotch tape to the inside-curve of a piece of CD-case cover.