This needle felting supply store sold me a 6"x9" piece of 1.5" foam for $6.66 shipped. Pretty good.
Cheap dremel-like-tool-that-broke case. Approx 6x9 inches.
Mouse pad covered with red silk on bottom.
Soft foam covered with red silk on top.
Gray foam with sharpened-tomato-paste-can holes.
Pro tip #1: I was able to bevel the edges of the gray foam with a belt sander.
Pro tip #2: Wear breathing protection if you attempt pro tip #1, for serious.