hes replacing the roof skin. i did the same on my eg hatch. sometimes it easier to take the roof skin off and glue a new one on. as opposed to trying to block out the whole roof. hes using a baller adhiesive its like 2000psi of bonding force. pretty cool stuff. structurally attaches while is seals. that way your not changine the properties of the metal causing rust really fast. hes definately a talented kid.