here is a quick and dirty method to make your own, for nearly no money and better yet, fully customizable.
Step 1: Making the Handles
the clay cutter consists of two parts, the handles and the line.
I use 50lb test deep sea monofiliment line, you can get 500 feet for about 10$, thats enough for 200 cutting tools.
you can use wood for handels, though it you use clay, you can make a bunch for nearly nothihg-- I use trim scrap and end bits..
a 4 inch cylinder, with two holes in the side.
the beauty of these is you can carve stamps in the ends, I have several sets that have my pot stamp so I never have to go looking for one...
Step 2: Assembling the Cutter
attach the two handles with about 18-24 inches of fish line with a surgeon's knot.
(loop though, make a granny knot with 3 wraps instead of two and finish with a standard square knot.
this cutter has a loop in one end for haning on a nail by my plaster wedging table (see my instructable "country potter- Plaster wedge table), and the other handle has a shape that creates a "seam" shape. becasue the fish line is water proof, if you want to clean them you can just chuck tham into a bucket of water, and not to mention, if the line breaks, or wears out, you can just fix it...
Step 3: Using the Clay Cutter
use the same motion to cut pots off bats, and add a little water to the bat and repeat the draw thoiugh so the pot will slide off..
thats it,... Ive made a couple hundred,by now...