VALVE, the company behind the Steam platform and Counter-Strike: Global Offensive needs to see these. The company allows users to upload skins to the Steam Workshop where other users can vote on whether or not they would like to see the skins added to the game. If it earns enough support and meets VALVE's standards, it may end up in one of the games cases.
Cases can either be randomly given out at the end of a game or purchased on the Steam Market from players who elected not to open the cases themselves. The market also allows you to buy and sell skins. Check out the five we can't believe VALVE hasn't added yet and let us know which one you want to see the most.