Jake was eager to participate in the Dr. Matthews project. Dr. Matthews kept explaining that Jake would be the tank, but Jake thought that his brain would be hooked up to the tank, and it would seem like he was the tank.
Dr. Matthews injected millions of self replicating nanobots into Jake. He was led out to a pile of scrap metal, and told to have seat. "What does this have to do with piloting a tank?" Jake queried.
"Jake, before you can pilot a tank, you have to build it."
"Huh! Hey!" Jake's clothing started to fall off in pieces as the nanobot in Jake'd body begin to metabolize the materials they'll need to build a metallorganic tank. The zipper, rivets, and button from Jake's jeans are gone. The nanobots have metabolized them, the minerals being absorbed directly into Jake's body.
Jake picks up a piece of metal to cover himself. The piece of sheet metal seems to be getting lighter, Jake sees that the solid piece of heavy duty steel has become a thin piece of foil. Jake realizes the foil is shrinking into his hand. The nanobots kick into high gear. Jake convulses and falls to the ground. He flails around, when he touches metal or rubber it is instantly absorbed into him. He screams.
Four hours later, Jake is barely recognizable as human. His legs are gone, replaced by a tractor tread. His body has become gun metal grey. He is currently swallowing some tungsten steel to be incorporated in his body armor, when the nanobots malfunction.
Suddenly his arms start to convolute into tractor treads, Jake is becoming two bottom halves of a tank without a turret or gun.
Dr. Matthews tries reprogramming the nanobots, the intial result is...