Andy, google "arbor press". Here is one result
http://en.wikipedia....iki/Arbor_press
I use a plastic kitchen chopping board as a baseplate, one of the white soft ones. They have a fine raised pattern on them
You only would need a small one, mine is 1 or 1.5 tons and it will cut out a gusset with no effort and the line length of a gusset must be close to that of your two valves. It will cut 6 or 7 deep as well. You could take your cutter and a baseplate to the shop and try the different sizes of press. The advantage of a small one is it can be stored when not in use. You could cut out a years supply for the most prolific maker in the world in half a day with a single action tool. Finding the right leather, now thats time consuming.
Anyone wanting tools to cut out valves or bellows parts, look for a person who makes clicker cutters for the shoe trade. Shoes are a bunch of leather shapes sewn/glued together, and the people who make the cutters are part of an industry that is centuries old. Mine cost about AUD$18 each. They work like a wadding punch and are really just a ring of sharp edged steel with a handle attached, which I hit with a hammer. Here is the outfit that made mine.
http://lucris.com.au...ew&id=20
Edited by Chris Ghent, 24 April 2012 - 08:33 PM.