Just thought I would throw in my 2 cents, I use a piece of finished ash that is 4x5 and is a little under 3/4 of an inch. I shaped it into a torpedo shape so that I could also use it for transferring craftaids as well. I stained it and then topcoated with 10 or 12 coats of poly to give it that slick surface. I have only tried the glass ones at Tandy but am always afraid of clinking them too hard on the granite and breaking them.