Two guitar pick designs, one plain and one with Pi on it because it looks cool. I've tried and designed many different picks but these two are the ones I keep printing and wear well over time. They sound more natural the more you use them as it wears according to how you pick! The third picture shows my two oldest and most used picks, and they sound great and feel really comfortable for me.

I have used these on electric guitars, acoustic guitars, electric basses, mandolins, and ukuleles with no problems. I have had the best results (least plastic-sounding) with matte or wood-fill filaments, but regular PLA works too. It just might take a bit more wearing in to sound good. Some light sanding can help but is not required.

I prefer thick and slightly pointy picks, so the plain one is 1.2 mm and the pi pick is 1 mm, but you can scale them in just the z-direction to make whatever thickness you want. I tweaked with the splines in CAD a lot to get them to look good and play well. 

Because they're so small and quick to print, I use 0.1 mm layer heights for the small rounds and chamfers since it doesn't add too much time. No supports required, especially for the pi pick which uses bridging to create a different texture for the bottom by having it offset.

You can also use whatever top/bottom layers, but I have found that the fancier patterns can result in more top ridges and affect the sound, so a plain monotonic or rectilinear top fill tends to work best.