I use a permanent flannel wall. First I attach sheets of insulation to the wall. One or two long screws through the center of foam sheet and into the stud. Then pin one edge of flannel to foam. Then use spray glue, (Scotch 77, I think) spraying a little at a time as you smooth the flannel over the insulation. (Cover surroundings with newspaper) Tuck in the ends and pin in place. I have been able to hang full size quilted quilts without a single pin. Held for over an hour till we had to take it down and move on to the next quilt.(We were taking pictures for a book.) I think what was important was that the flannel was securely glued to the insulation board.
For a portable board, I had a friend that attached the covered foam board to a header board. (Maybe 1" x 2") Then when she wanted to use it she hooked it over the closet door frame.