It's not quite the same, but...
A good friend of mine actually sent blocks to all of her guests for them to decorate and sign. They knew what her colors were, and most stuck with that plan. Many of them were not washable (paper on the blocks - one actually cut up the invitation and turned it into a beautiful block), so she made a really gorgeous wall hanging with the unwashable ones, and put the others on her bed.
I don't know how close to the wedding you are, but it's an idea!