In farm show (vol 35, no 3, 2011) there is a small article on Chad Travis' 2 level canner that holds 40 1 quart jars. It is 22x17", and 16.5 " deep, with a rack that holds the jars in place. It is 200 lbs with jars in it, so he uses it over a fire rather than the stove. He preserves fruits and veggies that require low pressure (low acid) like pears, tomatoes, and pickles. The set-up saves him a lot of time.