I got all the scrap iron I needed in Chelsea Court. I went to the teleports and did a circuit, after hitting all three areas realm hop in perfect realms. It took me two or three nights to get all I needed. The best times I have found to gather reagents are early in the morning or late at night.
Hey. You can find Scrap Iron along the sidewalks of Regent's Square - as well as Mist Wood. I was able to find lots of Scrap Icon in Chelsea Court. All you have to do is take the first right, and then keep going down until you get to end. The Scrap Iron should be behind the roof windows. If it's not there keep changing realms. I hope this helps.