Ruth,
I have a design wall made of flannel covered core boards. I love it! The flannel works most always but when I start layering fabric and I need to stick a pin in that's when the core board comes in handy. I'm a retired teacher so a flannel board just seemed natural to use!:lol:
This last week I decided I needed a flannel covered wall to hang some of my multiple projects so I don't forget them! I just stapled some flannel directly to the wall. Pretty soon I'll have the whole room covered in flannel!
My sister-in-law uses a flannel backed plastic table cloth that she had. She just tacked it up, flannel side out. Works a charm!
In a pinch my sister has used batting. I guess it's whatever's handy!