Wow, I have to say I've never seen such quality work from a scratch build with that kind of foam! I've worked with that stuff before (on things other than costumes) and its definitely fun stuff to use Keep up the good work my friend
See how i made the helmet out of vertical layers of foam, what I did was glued them together just along the edges and not in the middle. this allowed me to separate the layers once I got the basic shape done and clean out the inside. Here is another pic from my ODST build thats not in the video.
Oh and the foam is construction foam that I use at my work for insulating walls and floors.
you have to look at your local hardware stores. if they dont carry it check the insulation supply stores they should have some. its used to insulate walls and floors.
I'm amazed at what you can do with construction foam and a good paintjob, I'm loving the triangle side detail on the DMR and the foam method makes it look so easy to do. Good stuff.