My design wall is also portable. I used two 4' x 8' pieces of that green insulation board that Lowes sells. I laid one on top of the other and then used duct tape to tape them together at one edge. Next I opened them out and taped on the flip side of the duct taped edge making a good strong duct tape hinge between the two pieces. This gave me a wall that is 8 feet square when opened, but it can be folded to 8' x 4' if I need to move it from one room to another. It is not mounted to the wall since there is a dresser and a wardrobe in the way. Instead it leans against those two pieces of furniture and I use a couple of weights against the bottom edge to keep it from sliding. The insulation foam board is about 1" thick and is rigid enough to pin into even though the top part of the wall is not supported (it's taller than both pieces of furniture).
My wall is covered in black felt which came off a roll I already had. I used 505 spray adhesive to mount the felt to the boards on the front and pulled it around to the back and secured using duct tape. The advantage for me of using this type of board is that it can be pinned into. Individual squares stick to it without pinning, but if you want to hang a large top on it you can pin into it. I have also used mine for blocking art quilts. To do that I pin a piece of white cloth (a white flat sheet works fine) to the wall. Then using a 16 inch square ruler and a water soluble marker I mark one corner. This gives me a good right angle to use for drawing the lines that are the proper length and width of the finished quilt-- use the square ruler at each corner as you get to them. Next I pin the quilt to the wall using the drawn lines as a guide to get it good and square, spritz with water so it is damp (being careful not to spray your drawn lines) and manipulate any parts of the quilt that are still not square, or that don't lie flat. Let dry over night.
The black felt works fine for auditioning layouts, borders, etc. if they are made using light to medium dark colored fabrics.
I pin a piece of warm and natural or white fusible fleece to a section of the wall if I I am working with dark colored blocks or to audition dark borders on a quilt.
Flannel or warm and natural batting would work just as well. I'll try to post some pictures later today.
Rob
Last edited by rryder; 09-14-2017 at 02:30 AM.