Dude! Go to the bike shop and ask for a couple inner tubes that are heading for the trash. They might look at you funny, but say "recycling" and mention "clamping wood" and they'll go running for some. Cut the air nozzle off each tube. Then cut the tube lengthwise along the seams, so that each tube yields 2 clamping straps. You're good to go.
The beauty of these is that you can control the pressure (by how hard you pull) and you can apply pressure to every square millimeter of the bow. Also, once you have the thing wrapped, you can then use a couple clamps to fasten the stave into a form, and it will bend to take the shape you want.
You start the wrap at the center, and work out toward each tip. I always mark the center of each piece in the glue up: the backing, the core, handle pieces, whatever. When I wrap them with the inner tube, I start an inch or so each side of the center lines, so that I can align those marks to center marks on the form.
Here are a couple example pictures. Notice that you can also use stretch wrap. I usually don't however, since it's not reusable...but i was a dumbass today: i did two glueups, the first with inner tubes; i have more inner tubes, but I mixed the epoxy before i prepared the tubes, and so used the stretch wrap.
easy peasy
