http://4.bp.blogspot.com/-uFJJghcRJPg/Td1gqIclv9I/AAAAAAAAAG0/ik8Bl6XXJcQ/s1600/wheatley14.jpg

http://wireninja.com/wp-content/uploads/2010/06/Wheatley.jpg

So I'm thinking of making a Wheatley(Portal) costume for my head for the next Mcm Expo in October. However, I can't decide because of my slight inexperience as to what material I will use to make it. Any advice on what materials I could use? Ideally it needs to be lightweight because the thing is going on my head.