I'm old fashioned and keep my grocery list on paper and I've never found a good place to keep my paper while shopping. Since I couldn't find any solution on Thingiverse I whipped this up, a combined shopping cart token and paper clip/holder.
For this thing to be usable in other countries than Sweden I made it customizable so that any coin can be replicated. Click on the "Open in Customizer" button or download the scad file and open it in OpenSCAD. Before making a customized version though, take a look under the remix section to see if there is one already made for your coin.
You'll need a screw to complete this thing, size and length is customizable (I've been using an M3x16mm)