EVA foam (ethylene vinyl acetate) is like a high impact foam. It's usually about 1/4 of an inch thick. The stuff that we on the site have been using can be bought at Harbor Freight. I have one right here in westland so you could probably do a google map search for Harbor Freight and find one in your area. Anyway, the stuff they sell there is actually sold as floor mats and they interlocking puzzle style edges so they can connect. You can get a pack of 4 around $15 and they are 2 feet by 2 feet.
Also, to help you with your scaling, try checking out this thread: http://www.405th.com/showthread.php/31627-HaloGoddess-quot-How-To-Scale-quot-and-More-Tutorial It's a tutorial I made for the scaling method that I use. I've NEVER had any issues with my stuff by using this method. There are other scaling tutorials out there, but I believe this to be the easiest and faster way of doing it. :p
Also, to help you with your scaling, try checking out this thread: http://www.405th.com/showthread.php/31627-HaloGoddess-quot-How-To-Scale-quot-and-More-Tutorial It's a tutorial I made for the scaling method that I use. I've NEVER had any issues with my stuff by using this method. There are other scaling tutorials out there, but I believe this to be the easiest and faster way of doing it. :p