I purchased two new stamps.
Open the top of the sleeve, and cut off the fold to make the opening of the pocket. Slip your cardboard and stamp back into the pocket, and store them upright within easy reach and poof, you have a easy storage solution that did not cost a penny!
I store mine in a little wooden box. I am quickly outgrowing it. :) I love having them at arm's reach, and pulling them out of the sleeves helps to clean up quickly!