Use this instead of an American quarter to release the supermarket cart from the pesky coin operated supermarket cart dispensers. That way, you don't have to leave your child unattended while you return the cart to retrieve your quarter since you didn't feed a quarter to attain the cart. Before this neat invention, your alternative would've been to sacrifice your quarter (gasp!). Brilliant! Nov 24, 2012; CartRel2.stl added to reinforce attachment to keychain to prevent breakage. Enjoy :0) I invite you to visit 3dPrintFileMarket.com to enjoy more cool 3d print files. 3d Print File Market is not just another 3d printing website. It is the home of The Original Technology Accelerator App that will change the world.I can't stand how some people on Thingiverse upload stuff with incomplete instructions on how to successfully print it. Therefore, here are the complete printing instructions; Use instructions;