Rustic wedding idea: use rope-closured, leather bound journal as guest book. Books are easy to make, and you can get quick tutorials (or I can show you) off the internet. I used to make them sometimes for different events.
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How to make a leatherbound (could certainly use faux leather / pleather) journal, step by step. It looks like they've used recycled maps, envelopes and other goodies for the pages. Cool idea - it would also work with felt.