I'm with Chuck on this one. These are fun to make, and even more fun if you accept the challenge of doing them without having to buy a lot of stuff.
I start with a blank attached to a glue chuck with double-stick tape. I hollow the interior using a bowl gouge and scrapers, sneaking up on both the diameter and depth of the hole. Then, I remount the blank using my 50mm jaws on my scroll chuck, gripping the opening in expansion mode, to turn the outside. As Bobby suggested, it is possible to make the sides too thick - I find 1/8 - 3/16" to be about right. Too thin, and the wood flexes when you open the jar. Finish with a wiping varnish.
My wife buys marinara sauce in quart jars with one-piece lids that are interchangeable with standard mason jar lids. Most of what I have done has been to recycle those. You can also buy plastic mason jar lids at most grocery stores that also work well.
