On a camping trip to Baja California Mexico, I found an old rusted chili can on the ground. I thought at the time that this can appeared to be about the same size as a business card. Sure enough, after washing the can out, I was pleased to discover that a business card would fit perfectly into the can when inserted horizontally. I went to a local camera store (Nelson Photo) and my friends there help me find the right cap for the job (A Canon lens cap, thus the name "MexCanon"). I prepped and painted the can, made the pinhole and attached the shutter. I put a small piece of tape over the lip where the pinhole is located, so I would know where the front of the camera was when loading the camera in my changing bag. The exposure time in daylight using photographic paper is about 2 1/2 minutes.