This is about my 4th revision of this lid, all drawn in Google Sketchup. It snaps on very sercurely to many brands of soda cans, but is not quite airtight. Some cans will slowly drip if turned upside down. This is designed so you snap on the front two clips first, then the clip with the lever.

***Your print may fit too tight or not snap on at first, but simply take an exacto knife and scrape a bit of plastic off the clip with the lever on it until it works.*** Also make sure the channel is free of any debris or blobs. You may experience warping if you don't use a heated bed. Mine was printed on a a Solidoodle2 with abs and sliced with slic3r at .2mm layers and 25% infill.

I didn't intend for it to look like the radioactive trefoil symbol, but if anyone would like to see something like that just say so in the comments or remix it. The sketchup file is attached. The main picture was edited with paint .net just for the heck of it. It's a great free alternative to photoshop. getpaint.net