There is a block of three strips of fabric. The center strip would be a muslin or a light color so that people could write on that strip. It actually is a quilt that you could put together and have them sign the top at the wedding. Or you can chose to just take blocks along.
You cut strips 2" by width of fabric, Three of them for each strata, sew them together with the light strip in the center. Subcut the strata you have sewn into 5" blocks. Place one block horizontal and the next vertical for each odd number row.. The next row or even rows, place the first block vertical and the next horizontal etc. It makes a wonderful scrap quilt and can easily be made any size. The finished block will be 4 1/2 inches.
The actual room they have to write on is 1 1/2 by 4 1/2.
If that is not enough room for you you could cut your original strips 2 1/2" by WOF and then subcut into 6 1/2" blocks. You finished area to write on would be 2" x 6". The smaller makes a prettier quilt.