I started a version of my own a long time ago (when Iron Man first premiered) but I found I was lousy with doing the complicated shaping and moulding necessary for the Iron Man armor. I've thought about it again a few times, but as BlackAce said, it's pretty complicated. My best advice is to pick up the tools available for modeling for your version of the sim and start fiddling. You may not get exactly what you're going for, but you'll definitely get a nervous tick associated with the project.
