Mine were all homemade, often looking for just-right forks in branches.

Used cutup inner tubes, wide rubber bands, latex surgical tubing for the bands.

Leather from various sources for the pocket.

Ammo varied from rocks to marbles to lead balls, whatever was handy.

Pretty good with it, only used it for targets like tin cans etc., never to hunt anything, never shot at a person.

Larry

P.S.: And ball bearings whenever I came across them.