For the most part, my collection of Funko figures stay in their cases. But there are some that NEED to be freed from their cardboard confines. For those, and for my collection of custom figures, I like to display them in cases. Since my space is limited, I prefer display cases that can hang on the wall.
For my custom POP! figures, I like to use baseball bat cases. These cases are available in-store and online at Michael's. Each case can hold up to 13 POP! figures inside and even more on top. I like to display some of my in-box ones on top of the case. The cases can run a pretty penny at $59.99 each, but with sales and coupon stacking, I've been able to pick them up for as little as $24.99.
I also collect Funko Dorbz and Mystery Minis. I've found the best way to display these is in shot glass cases. Each case can hold 28 figures inside and, like the bat cases, you can display even more on top. The shot glass cases are the same price as the bat cases, but can also be purchased at a more reasonable price if you keep an eye out for sales and coupons.