Thanks for the interest and comments.
Gwyntog you asked how!
Rough turned and hollowed from quarter log and allowed to dry, remounted and turned till true, but still about 7 - 10mm thick,
First cut on the band-saw holding the piece in a purpose made cradle attached to a board with a guide underneath to run in the guide slot of the band-saw table.
both surfaces made true on a 12inch disc sander only sanding away enough wood to the thickness of the insert, (important to get a good grain match).
For the gluing process I used a slow setting two part epoxy resin as lining every thing up seem to take me a little time, this is the most important part of the process and for me the most difficult, although the shape of the piece made it easier to clamp.
Repeat the cutting and gluing process two more times (or more, or less)
When all adhesive is totally dry remount and turn and hollow to your final thickness. (in this case because of all the gluing, 5mm to be safe)
Dave.
PS you asked the size. click on this link
http://www.flickr.com/photos/67072953@N02/sets/ then on Woodturning set.