From US Night Vision comes Mag Wraps – Rapid Wraps. The Hot Shots Calendar Girls wraps come with two per pack at $14.95, all others are packaged with three wraps for $19.95. Many styles are available on their website. They even do custom runs, I believe a minimum order is $50 wraps.
While some are looking to decorate their airsoft rifle, others to add camo to their hunting rifle magazines, competitors often like to add color, but I see the best use as differentiating my mags from my friends when we go shooting. I have one friend that often goes home with a few of my Magpuls so I stopped taking any Magpul magazines when I shoot with him. This seems less passive aggressive than drawing all over his FDE mags with a sharpie.
While we didn’t use the wraps ourselves, USNV has a video up to show us how they work.