This grip is designed around the Xbox Series X (I believe) controller model. There are a couple of options:

For the Switch Lite: Single: both sides are separate, Connected: with a press-fit connector.

For the Switch Classic/OLED: Single: This model has not been tested in real life by me yet, but it should be okay. It should be dockable. Connected: with a press-fit connector (different for switch and switch oled (not tested, I used dimensions found in the internet))

You have to flip the model to the flat side, and I recommend moving the seam from the front to the back according to the screenshot. No supports are needed. I printed mine with 5% infill and 2 walls for testing, and the connector with 20%. I can make a connected version for the regular Switch if I receive feedback.