When I was wrenching for the army in Germany, they used to sometimes give us 12-14 end wrenches restamped 1/2 - 9/16 that almost fit. I forget who supplied them, but I think it was the same outfit that used to make VW jacks. They worked OK as long as you didn't tighten the bolts enough. The wrenches seemed to be made of spring steel and the jaws would pop open with a lot of torque.
