A Cansolidator holds cans and will rotate them for you. The product is made out of plastic and has enough "moving" parts that you can customize your rows to fit the sizes of cans you use. The Cansolidator can be found at Shelf Reliance, http://www.shelfreliance.com/modern, I've seen products like this advertised on the internet from other companies, only those have been made out of cardboard. The price is about the same. I'd rather have the Cansolidator than cardboard! Shelf Reliance has three different sizes of Cansolidators to hold 20-40 or 60 cans.
In the 80's when home food storage became a craze, we built shelves but had the back a bit higher than the front. This made the cans roll to the front. All worked fine except you had to be able to walk around the storage rack to put the cans into the back. Shelfreliance.com also has free standing units but you load from the front! Since I already have shelves, the Cansolidator would be the right one for me. I've also seen examples on the internet where you reframe a wall and start the cans at one end and 10 feet later at the other end of the wall they come out. This is a great idea for the do it yourselfer.
ModernSurvivalOnline.com is holding another contest, ModernSurvivalOnline's Cansolidator Giveaway. I wonder if they have a limit on how many times I can win? I hope not. But, I did win their Non-Hybrid seed giveaway which I promise I'm going to plant the seeds and see how things go. Even if Rourke says I can't win anything else for a while, I like their website and will post information on their contests anyway! http://modernsurvivalonline.com/ is a good site. It's in my list of favorites.