please excuse the delay in replying I've been away on business. The cutter is a blatent plagerisation of one I spotted on line - I think on the forums at Cheesemaking.com. It's a wooden dowel cut to length, marked in cm and with a rigid wire at the bottom to cut the curds. A butchered coat hanger donated the wire
It's varnished to protect the wood and actually cuts very well giving nice regular cubes. As you mention the vertical cuts are made in the normal manner. I made a guide/support that sits on top of the pot keeping the axis of the cutter centrally located.
Making this commercially would be difficult I'd imagine as the diameter of the cutter has to match that of the pot being used.
I'll try to post more pictures on my next make. Cheers, GD.