Punch top of it with oval punch. Smooth corners with nail file or just round them with scissors. Use corner rounder on bottom corners. Glue mini popsicle stick to back at bottom. Use white gel pen to add accent.
I love this idea. An envelope guest book. You just take a store-bought scrapbook/album and glue envelopes into it. Lay out colored pieces of paper for guests to jot notes down on, and then they can place them in the envelopes.