This is a travel controller for the Nintendo Switch. The Joycons just friction fit into the slots on the sides and it's good to go! Very comfortable to use and helps with the reach from the right thumbstick to the ABXY buttons.
Full article on the project is here and you can follow along with my 3D printing shenanigans at https://www.saltfabs.com
E: May 7th 2017; fixed some naked edges in the original model
Update: February 12th, 2018: Uploaded a split version of the controller to eliminate the need for supports. Just print out 2 copies of the "flat fit half Switcherang" and they can press fit or be superglued (cyanoacrylate) together. There should be enough space in the female spots to accept a drop in each one.
A little rough around the edges on quick print settings, but easily cleaned up.
"Flat Fit Half Switcherang" eliminates the need for supports.