I made a wedding memory wall hanging for my GD. She wanted blue and he wanted gray so I got a jelly roll of assorted blues and grays. Used a pale blue for the signatures. Ironed the pale blue with freezer paper and cut into 3 x 6 strips. Using a washable marker(crayola) I drew 2 1/2 x 5 1/2 rectangles so people would know to write inside the lines. a #5 Micron black pen worked well. Some people wrote messages and one went out of the lines. I would suggest having someone at a table to instruct the guests and make sure they don't walk off with the pen. Have 2 or 3 of them handy.