Credits to manabun on Thingiverse for the great original design!
Original:
https://www.thingiverse.com/thing:2769344
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.
You might want to print the grips with a brim.
Comments advised to scale a bit. Since 17-1-2022 I updated the models for the right fit.
Tip: Only print the lower sliding bit first to verify the fit before printing the whole grip.
The author remixed this model.