A pair of hat racks mounted vertically. Or you could just take a couple of strips of 1X4 lumber, drill holes in 'em and glue in 3/8 - 1/2" dowels. I'd make them about 6" long to give enough room to put 2 bows on the same level. Even if you don't have that many bows right now it doesn't mean you won't ever accumulate more.