google turning videos or jamb chuck. lots of info out there. a jamb chuck is nothing more than a hunk of wood turned with a slight taper to fit the inside of your bowl or box or most any hollow form. just mount a hunk o wood on a face plate and turn it to fit your piece, then jamn the piece over that and bring up the teil stock to hold it in place. for non hollow pieces just hollow out a hunk o wood so your piece jambs inside of it. there are a ton of you tube videos.