Basically extends the height of the joystick to allow to perform small and precise analog movement easier. There are two versions; concave and convex. The idea is based from modded pro-gaming controllers that have extended joysticks for the same reason.
Thanks to Nintendo Switch model currently available, making this mod is easy as pie.
Your support will be appreciated.
Also, if you don't have 3D printer, go to http://3dhubs.refr.cc/8BSLKTK for quick and easy 3D printing service. Thanks
If it is loose, put a small piece of paper between the joystick and the mod.