i have a strip of cork that runs under my fabric shelves so i can tack things up.
you know that contact paper cork board with the sticky back?
i just cut it into strips and used a couple layers so it'll hold the pins secure
i've had it up for a few years now and it's still holding pretty well.
i painted it the same color as the walls to help it disappear.
it's a really great way to keep and display things i'm working on.