This shopping cart key/coin was designed for European shopping carts. It is strong and has a special shape that fits perfectly into the opening of shopping carts. After the shopping cart has been released, the key can easily be removed again.
I printed mine with bambu's strength print profile, 6 walls and 25% gyroid infill and after lots of testing none have broken yet.
I hope you like my model, feel free to post your prints in the comments!