I used 2 of the 4'x8' insulation for the base of my design wall. Then used duct tape on the front and the back to make a hinge ... I actually made the hinge starting with them together so I knew it would fold properly.
Then I put down papers in my garage. A friend came over and we cut the BATTING to the size of the whole design wall plus enough to turn under to the back side of the DW. We then folded the batting into a neat little bundle the width of the DW and used the 3M Super 77 multipurpose adhesive spray - bought an an office supply store and not a LQS - this is NOT the quilting/fabric spray! -on the DW then carefully put the batting in place. Note: it really is extremely important to have 2 people do this unless you like challenging your vocabulary and such.
Once the batting was on we folded the DW and secured the edges of the batting to the wrong side of the DW.
This DW is folded behind a tall bookcase in my living room. I did put plastic around it to keep it from getting dusty. Then I draped an afghan covered by a mola over the exposed area and it is now a design element in my living room.
I used the 2 pieces of insulation as I wanted a very large DW. There is no reason you can't use less for a smaller DW.
ali