I made this Pokéball switch game cart holder from scratch. I printed one of the existing ones on Thingiverse, but I had to do a lot of post processing to get it together and in the end, the latch didn't work at all. I looked to modify the model, but after much fiddling, I gave up.

For a quick preview of this project, check out this short video:
https://youtu.be/R7knSxRuAK4

I made a video for how this thing assembles and you can find it here:
https://youtu.be/0vRFBtplHTM

Features that differentiate this from other models are:
1) Hinge is more forgiving and beefier.
2) Hinge can be made functional by using a piece of heavy paper clip or similar wire. I used a finishing nail for mine. I don't suggest drilling the holes through on this as the torque from the drilling will likely break it. If your choice of hinging pin is tight, you can use the following technique to clearance the hole. Use masking tape to hold the inner shells together to line up the hinge. Then, use a heat gun to heat up your pin and push it through the holes. You will need to pull the pin out, reheat, then press it in again. Repeat until the pin goes right through and slides nicely. Once in, use a dot of glue gun glue on the ends to hold the pin in place.
3) Flat bottom and top inner parts rather than full spheres to save on print time and material.
4) Cart slots are looser than other examples. I didn't want to damage or wear out the cart plastic or labels, so I intentionally made them loose.
5) There is a flat surface on the inside top lid that will prevent the carts from falling out of the loose slots. They may rattle a bit if you shake the ball, so a piece of thin foam or fabric glued to the inside roof of the lid should hold the carts in snug.
6) Latching mechanism works nicely. Other models I tried were made with tolerances my printer was not able to accommodate even though my printer is quite good for that. This design is bigger, but it's more forgiving for some less than perfectly accurate printers.
7) I liked the Switch logo in the top lid I saw on some models. However, they again had zero tolerance for fit, so I gave them some allowance to fit better. If they are not quite a perfect fit, I suggest placing them in, and then give them a little blast of the heat gun and press them in with your fingers to fill the gaps. I also included a non-logo version of the red part in case you don't want the logo.
8) The size of the ball is a little different from other ones here, so I made a new holder for it. It's pretty well a copy of another one I liked, so I just made it to fit this size ball.
9) The compression springs I had we're a little bigger diameter than a pen spring, so the holes in the button mechanism to contain the spring is a little larger, but a pen spring should still work.
10) Some of the other models either didn't spring open or required a torsion spring. Since torsion springs are not in everyone's inventory and require the perfect amount of torsion to make it open nicely, I made this one work with two hooks and an elastic band. This way, you don't have to notch out the hinge and weaken it for a torsion spring. There are multiple slots in the inner black parts to accommodate different strength elastic bands. Refer to the video for how to put this part together as there are some techniques in there that help make it reliable.
11) I saw someone put slots for micro SD cards which I thought was a nice addition. The slots are slightly over-sized which means depending on your printer tolerances, may be a little small or a little tight on such fine items. For me, it was just right. Orienting the SD card one way fit more snug than the other way so give that a try too if the fit isn't great.

Tips:
I suggest printing the black parts flat (cart slots up for the bottom and ring part up for the top) and with supports and 30% infill. Red and white sphere parts should be printed edge down for best results. Be mindful of the arced white parts. Slice them with flat sides to the bed. All of them have at least one flat side to use. This will prevent post processing time and allow for higher quality prints.

See screen shots of Cura layout if any of this is not clear.

I used tree supports in Cura for this so it was easier to remove them later.

I mixed my material types for this print. The black parts are PETG as they take more of the stress and wear and tear of use. ABS is strong, but brittle so PETG is a good choice here. The red and white parts are ABS. No particular reason for those to be in ABS other than the PLA red and white I had were more translucent and I wanted it to be more opaque looking.

Credits for inspiration:
https://www.thingiverse.com/thing:2947088
https://www.thingiverse.com/thing:411193

Update:
January 7, 2018
Modified inner parts to not have a lip around the inside to make post print clean up easier.
Fixed the button not being perfectly centered in the Z direction.
Some other general clean up of small details.
Added locates around perimeter of inner black parts and spheres so getting things lined up and glued is easier.