A place to store all your gun skins. For example : you've got a Gang Skin for your BAR, and you're bored of the skin, without having to completely to lose the skin, you can purchase a different skin. Still keeping your previous skin if you want to change back to it. this could be an option you can purchase to keep all the skins you've purchased/earned, and not lose them. If for example you accidentally grabbed another skin, and now your Gang Skin is gone. I believe it could come in handy, like if you got a Gang Skin and you want to change to diamond/gold BAR, you can still keep the skin in your library and get the skin you want. Since some Gangs sell their Gang Skins, and you have to be in gang for 28 days with 5 star rank. And if you lose it all your spendings and time is wasted. To avoid that and store all your purchased/earned skins that are stored in one place safely, you can freely change skin to your needs.

There's much to play around on this concept I'd leave that to the developers. this is just a useful thought I had, I wanted to share it, maybe it could be implemented.
Hopefully this makes sense lol.

Criticism is appreciated!