It looks like it was printed full size on 18 x 24 foam core board (something I recommend clients do at Fedex Office, which used to be Kinko's. They do a good job.) and the guests are signing on the background, which is the couple's wedding color from 1962. My client (their daughter) told me she printed the party-favor versions (I send a sheet with every commission) on magnet paper and gave them to guests. What a great idea, I'll be sure to tell future clients that one. Thank you!!
Here is the artwork:
Congrats to you both!!