What is it used for?

My son came into a bunch of tools from a deceased in-law. The tool's owner was an aviation mechanic. My son and I both, are Aircraft inspectors (IA) and my field of expertise is structural repair (sheet metal). So, obviously I was very interested in what sheet metal tools there were. I found, what is pictured, in a large assortment of metal working files. It is about 18" long and 1.5" at its widest point. It "very" smooth on both sides, has sharp edges and is fairly heavy. It was manufactured by the 'Mound Tool Company." I'm guessing that it was used to work body lead. What say the tool experts?

shaping tool.jpg

shaping tool1.jpg