My brother and I were the source for the large 1/2" wide X 6" long rubber bands that all the neighborhood kids wnated for their slingshots. My mother worked at a drugstore/office supply and she could get them for us by the box. We originally used Y shaped handles cut from trees, but later came up with a handle cut from 3/4" pine. Leather from shoes or boots. Also got heavy cord to connedt the patch to the rubber bands. Used smaller rubber bands to attach the large rubber bands to the wood handle. Made for some really good trading stuff.
My kids used wrist rockets with the round surgical rubber. I had almost forgotten about the old wrist rockets till I found a handle in the kids old junk. My wife had some surgical rubber tubing that was suppose to be for "working out" around the house. Yeah right like she ever worked out with them. I confiscated them and refitted one wrist rocket a few months ago. I was suing it to run off the M in laws smelly old dog. Still shoot it instictively, except now I have cast lead balls instead of rocks.