There is an article in one of the back issues of American Woodturner that covers this quite well. Basicly all I do is glue a blank to a waste block, turn the top, drill out an appropriate size hole, part it off the waste block, make a jamb chuck, reverse the blank and finish off the bottom. Lamplight Farms sold them for 99 cent each, but their web site has been down for "reconstruction" for a while. There is another web site called Woodworking Friends that I linked to from woodturningonline that has a lot on information on them. You can also get information from www.woodturningonline.com. Just click on their turning projects. Didn't mean to ramble. Lack of sleep and good sinus pills.
Dale