Normally, I do not spend much time on Facebook, but have to thank my friends for sharing the advertising of Cartridge Keychains, a small paracord business who adds a small twist, the incorporate bullets into their work.
Their offerings range from standard bracelets, to slings (both single-point and double) and they offer the standard array of customization of colors. All items are made-to-order including the caliber of incorporated bullet.
Check out their website and go nuts customizing your next sling. My wife was a fan of the pink womens sling.