My design wall is a layer of headliner foam, covered by a layer of batting, covered by a layer of flannel; all thumbtacked up to the wall.
Things stick to the flannel pretty well, though I do slide a few pins in if I'm putting up anything larger than a couple blocks.
I also tend to work on multiple things at once, so often I will decide I need "more" design wall - usually I don't want to take down what's up there but I want to work on something else - in that situation I pin a large old bedsheet up over the current work and then roll out another spare batting I keep on hand and pin that over the whole shebang - now I have a fresh design wall layer! If I need to get at the layer below I can just pull the bottom of the bedsheet out a bit (it's very long) and fold it over the bottom of my new design wall and then roll those two layers up - the sheet keeps the blocks from sticking to the wrong side of the batting and it can all be unrolled again neatly when I am ready to go back to project #2.
It's a little crazy sounding but it really works for me. I often have "my own" project going but work on simpler things with my "students" so it's very useful for me to be able to switch between projects or create a fresh space for someone else's work to temporarily reside.
And yes, I thrive in chaos. LOL!