Make your own slingshot by 3D printing the main parts and using a balloon as a rubber. We used to make this kind of slingshots when were kids by using the hard part of a toilet paper, tape and a balloon. You have to cut off the 1/3 of the balloon so it can fit to the tube.
Supports or rafts: This part does not need supports or rafts.
Perimeters: Three lines perimeter.
Layer Height: Medium to high.
Printing speed: High.
Travel speed: High.
Low-cost PLA with unique colors: