I've wanted to try this for a long time to add to my food storage. You can can butter and it turned out wonderful! It's very easy and really doesn't take a long time. I bought some butter at Sams and 4 pounds will make 5 pints of butter. You warm the jars in the oven for 20 minutes while you melt the butter. You also boil the lids to get them hot. You then pour the butter into the jars and put the lids on them. After they seal, you may want to turn the butter a little to bring any air to the top. It's that simple! I figure it cost about $1.35 a jar.