On my trip to Aldi this morning I realized I did not have a quarter in my car and was forced to carry my groceries in the bags I brought with me to the store. I came to printables to find a solution for this and did not find any that I really liked so I made my own version. I would suggest printing with a .4mm nozzle .2mm layer height and 100% infill.

** V2:

I adjusted the diameter around the outside of the key ring hole and also increased the diameter of the keyring hole to make it flip around in your pocket easier. I also increased the thickness by .25mm to make it an even 1.8mm thickness for better slicing.