I make flats from latex-based exercise bands that I purchase at Wally World because
it is cheap and you get a lot of material for the money
no worries if I screw up my cuts - I just grab another length and try again
3 band weights - light, medium, and heavy - as a target shooter, 3/4" heavy in a single band or 1.5" medium folded in half shoots 3/8" steel shot with surprising zip
Wally World is also my one-stop slingshot supply destination - #107, #64, and #32 rubber bands in the office supply aisle, also glue to mount paper targets on heavy cardboard, and double sided tape to help align bands when tying onto the slingshot, right next to the fabric aisle for fake leather, right next to the hardware aisle for duct-take to reinforce the fake leather ("urban leather") and paracord and twine for lanyards, Daisy steel shot and marbles in the outdoor aisle, along with Daisy and Barnet slingshots for modifying, and paintballs, which is right next to the exercise aisle for the exercise bands and also grip tape. Balloons in the party aisle make great targets. If I am feeling truly ambitious, I purchase some baby powder and a plastic funnel, pour the powder into the balloons before blowing up and - reactive targets. Also use the baby powder to lubricate rubber bands when I make bands out of them.