Modified my original switch game case to use as a travel joycon grip! Also now holds twice as many games! Perfect for travelling and playing on the go.
For the shell, I printed it vertically so there were no bridges or supports needed. The grip also has the same snap lock features that are on the real joycon grip and switch, so you have to use the release buttons on the back of the joycons to take them off of the grip. For the logo, I printed it out separately and gluing it onto the shell.
Note that there is a tab on one edge of each compartment on the case that works as a friction fit snap feature. Push the side of the game cartridge against that tab and pivot it into position to lock it into the case.
Update: I've fixed the updside down logo of the original version and uploaded a version without a logo at all in case you didn't want to include that part.