I don't recall ever seeing one advertised for sale, in catalogs or magazines.
I found one at a trap convention years ago, it was hand made to fit a 1 3/4 size trap, B&L or Victor style.
A tailgater had the thing, I picked it up and looked it over, it had been hammered on a bunch. Was a long time ago, but just guessing it'd weigh over 5 pounds. Forget, the guy only wanted 10 or 15 bucks for the thing. I wish now that I'd bought it, it would make a good boat anchor for slack water.
I'll try to describe how it was made, the cutting edge was made of (give or take) 1/4" flat metal, sharpened on the inside. It had a sort of "frame" which braced the jaws side-to-side, and braced the ends which would cut out for the spring levers. Each one of those pieces were braced to the main shaft, where you'd pound.
This is how I looked at it, if you set even a small trap, say a 1 3/4. If you'd take a pencil and trace around the trap, you're dealing with over 20" of cut.
Maybe you can relate to using a pointed shovel, a "ditch shovel". Where you can bear down and put some weight on the handle and stomp it with your foot, and you're dealing with a thin edge, and only 6 or 8 inches of cut.
Cutting through sod or rough hard ground, it'd be impossible to drive it down. It was a neat looking contraption, but for my type of soil it would be worthless.
If a couple of you guys have one laying around, get us a picture when you get a chance.
If I was going to design one for a bigger trap like a #3, I'd make it half the size of the trap, from the trap's dog to the opposite jaw. Then you could flip it around and cut out for the other end of the trap. If your soil is nearly the same consistency as cookie dough, it should work good!