Credits to manabun for the great original design!
I modded the design to be printable in a better position without support. The slot is slightly modified for an easier fit for the joycon.
The shoulder buttons are also modified for a tighter fit in the grips and have a more comfortable shape to the fingers.
The fit is excellent on my printer but can be very different on yours. So scale it down a bit in your slicer if the fit is too loose and vice versa. Tip: Only print the lower sliding bit first to verify the fit before printing the whole grip!
I printed the grips without support with a 0.6 nozzle.
The shoulder buttons do a bit better with support from the bed and a smaller nozzle.