Concave PSP thumbstick

This is a combination of https://www.thingiverse.com/thing:2057369 (used because it saved some time modeling the top, but it limited D-pad access and got stuck a lot) and https://www.thingiverse.com/thing:3048385 (because it grips the base well).

I flattened the top, made it comfortably concave, and balanced the height as part of fusing the source pieces.

The "more clearance" version is half a millimetre closer to the PSP's body and half a millimetre further away from the D-pad. It's not quite as comfortable for stick-heavy games, but for cases where the D-pad is used a lot, it helps with accessibility.