Making the Rusted corrugated metal sheeting .First you need some corrugate metal .I use the one from sodders Enterprises at or you can use northeastern and you need Radio-shack PCB Etchant solution cost about $9.95 .Ok so you have all the item let get rolling .First get two plastic can one for water one for the solution.Now cut the metal to size you needed to do roof you can cut then to scale after your done . Now wear rubber glove and in In a well-ventilated area with a fan or open air vented room or out side.Always wear goggles, gloves, and do not inhale the fumes. Do not use any metal containers, measuring cups .Put the metal in the solution and wait 30sec to a min your see it start to boil and smoke at this time work fast and remove it with Dermal Anchor Piercing Hemostat Forcep TOOL .or needle nose and into the water for 5min then put on paper towel to dry it be dark gray first but it turn into rust when drying . now clean up can and wash hand good .Please read This etching solution, while made with common chemicals, should command respect. It is dangerous to yourself and surroundings, treat it with respect.