One small step for man..

[kakomu]

Get your self a large piece of Wood, and mount some Metal to the top of it. Place the pad on top of the metal and stretch it out to make it perfectly flat, then place a little padding (no more than 1/3 thickness) underneath the 4 stomp areas (there's probably a special DDR name for them), and it looks like you have a good makeshift DDR hardtop mat (no need to spend $100 or more for those ones on line).