I like the error. It makes it more hand made and special.
But as for the design wall ... I got a sheet of Owens Corning Fomular (Pink Insulating Sheet for walls) from Home Depot (DH will like shopping for this) and I covered it with felt from Joanns (40% off coupon) plus a sheet of white muslin to prevent the pink from showing through and pinned it to the back and voila, cheap functional design wall. It weighs ounces and I move it around the room as needed.