I've made one for myself. Ended up using a couple of hundred feet of paracord in order to layer enough cobra weaves to make the area that rests on my shoulder wider/more comfortable.
I can't speak for the ones the other member made, but I like mine a lot. Very comfortable, and it's nice having that much paracord available in case it's needed.
They are definitely cool lookin, and having all that paracord handy might be nice, but they sure wouldn't be very easily adjustable, and wouldn't be any good as a shooting sling I wouldn't think. I like all my slings to be capable of that.