Finally made a proper design wall! And with the husband's help, we (really he!) hung a drapery rod above the design wall to hang my finished quilts. The rod is long enough that I can hang 2 quilts - and one can hang in front of the design wall when I'm not using it.
The design wall is 60 x 80 inches. I searched several blogs and watched a couple DIY YouTube videos... then went my own route.
I purchased 2 large pieces of foam core (40 x 60 inches) from my local art supply store and taped them together. Then I purchased 6 yards of white flannel from JoAnn's (used my 40% off coupon). I really only needed 5 1/2 yards of flannel. Also, they do make a flannel that's 60 inches wide, but that would not have been wide enough to stretch over the back of the boards, so I purchased the regular width and pieced it. Then I stretched the flannel over the back of the foam core and taped it. Nailed the covered foam core directly to the wall. Very happy with how it turned out.
Above is the beginnings of an improv quilt. Below is step two... still a work in progress.
One more thing... I purchased these clips for the drapery rod, so I don't need sleeves on every quilt.