You can do a search on here for aprons or saddles and find several for sale, as well as threads on how to make your own. I just cut a rectangle of polarfleece or sweatshirt fabric with two slits on the sides for the wings and hook it over their wings. No sewing needed. There only needs to be about 2" of space between the wing slits. You can also simply duct tape their backs; this is left until it falls off. I would not do this to a completely bare spot, though, only to torn up feathers.
