You my friend are a friggin genius with talent on tap. Thinking outside the box to use floor pads to create this incredible armor, and all the other armor you've done is sheer genius. Glad I stumbled across your page.
There are different grades and brands of foam that will give slightly different effects. The foam you see in the photo is still in its "raw" state,.. here it's only been warmed with a heat gun. (which causes the foam to expand and then shrink slightly causing the surface to become much tighter/smoother) Also many foams have surface treatments on one or both sides. (usually a patterned or smooth layer of rubber) Many can also be sanded with fine grit sandpaper or carved with a dremel.
Dirt cheap. Pack of 6 sheets, 2 x 2 foot each, 1/2 inch thick costs me about $12 USD. You can also order larger sheets to just about any size/thickness/color you need from various distributors online. Just google "EVA foam sheets".