I made my first sling four or five years ago while attending an art class.
One day the teacher was sick and as a result noone was doing anything, so in a moment of inspiration
i cut two pieces of thin leather about 50 cm long/1 cm wide and sewed them on a small square piece of slightly thicker leather.
I dident make a finger loop just held it between my fingers and slung away.
I nearly killed myself with the first couple of throws slinging straigt up or barly missing the back of my own head during the windup, but eventually to my great joy i hit a roof of a small outhouse knocking a piece of the grassy earth it was covered with. i have been slinging on and of ever since