I have one, it's an antique, made by an uncle when he was a boy in the 1930s. It's made from the fork of some small tree branch, dunno the wood and looks like inner tubing tied to the prongs. The rubber still seems workable but I haven't fired it for 40 years and doubt I'll ever test it again. I was a rubbish shot with it anyway. Just kept it for sentiment, it doesn't take up much room.
Many kids had them, boys anyway, even in the city when I was a kid but they gradually clamped down on them and they're essentially banned now.
We called them Shanghais, pronounced Shangeyes, dunno why. Even though banned they're still sold on eBay, or were a few months ago when I stumbled on some. Might be a problem with customs here though.