1 Euro shopping trolley chip
Due to makerbot blatantly stealing peoples work and filing patents I will no longer use thingiverse.
Get it from here instead:
https://www.youmagine.com/designs/one-euro-trolley-coin
1 Euro shopping trolley chip. Simply, print it, put it in your key ring and away you go, ready for shopping.
If you print one for you comprehensive partner he/she will also understand the usefulness of your 3D printer!
If you find it useful and you wish to customize it, let me know and I will upload the scad files.