Well, I don't have any way of getting photos on a computer, so I'll try to describe: a friend gave me a little old original day horn; it came with two short pieces of brain-tan deer hide roughly 1" wide. There is a staple in the pine butt plug; that butt-end leather strap, about 7" long, has a slit cut lengthwise in each end. Horn end slit is only about 1" long; the strap loops around the staple, and back through itself. The free end has a slit about 7" long; the woven shoulder strap feeds through that slit, and just gets an overhand knot for adjustment.
Spout end, the leather strap's shorter; has a slit to (barely) slide over the little hump behind the spout; free end has another slit cut, similar to the butt-end; shoulder strap feeds through the slit, and gets another overhand knot.
It's not super-finished looking, but it's comfortable, adjustable, and the rustic approach fits this horn's use: squirrel-hunting.