Welcome to the Quilting Board!
If you have a large window, sometimes those plastic clothes hangers with the clips for holding skirts etc that come with clothing bought at most stores work great. Just hang the hangers off the curtain rod and clip the quilt or design wall (mine is also a flannel back tablecloth) up with the clips.
I love my portable design wall, which leans just enough so practically nothing ever falls off. I almost never have to use pins. Just buy the 2" think pink styrofoam insulation that is used in basements, etc. (home depot) Cover with Flannel. I made covers like giant pillow cases and covered two of the 4x8 sheets of foam. then hand whip stitched together on one edge. I covered them so that one side is light blue other side is dark green. nice to switch depending on what value of blocks you are auditioning. so they stand out.