I just tack up a flannel backed vinyl tablecloth and use it.

If money wasn't a problem and I really needed something portable - maybe. But I think it's too expensive and too small.

A couple years ago, Michaels was having a sale on artists canvas. Bought the biggest one they had and covered it in flannel and hung it on one wall.

I use the bed in our guest bedroom, lol. Cover it with a plan sheet and lay it out. Works perfect for me.

I saw directions on a blog recently for making smaller design boards. The insulation panels are available in smaller widths-- maybe 18" X 4', with tongue and groove slots for interlocking. Apply batting (or flannel) on the front side using spray adhesive, trim to reveal the slots, and mount to the wall with 3M Command strips. You can add or take away boards as needed.

I have a Block Butler semi-permanently up on my wall. It has a slightly sticky surface that works really well. It has helped me so much in the last 2 years that I cannot imagine how I survived without it. When it is not in use, I cover it with a wall hanging.

I hang a vinyl tabecloth backwards on the wall when I need a larger design wall. For smaller things I put a piece of dowl thru a tube of a piece of batting and hang it over the door to my sewing room. Works great for complicated blocks.

I got four large pieces of cardboard from Costco, taped them together, and blue-painters taped white flannel fabric over it. I move it around the house where ever I need it. I wash the flannel frabric whenever it gets too thready. Hmmm... I wonder if this might make me a redneck? :D

just hang some flannel on your wall and you have a very affordable design wall.

Last week I purchased a portable sketch board 18" x 18" made from masonite at Hobby Lobby for $9.99. Covered it with black fleece (held on with medium binder clips for easy color and washing changes). I take mine to UFO's and guild meetings for working on blocks. It has saved me alot of ripping out.