I made one for my sister's wedding last year. I cut 8.5" squares and machine appliqued a heart on each corner so when the blocks were assembled the hearts formed flowers at the intersections. I used a light back ground and medium to dark for the hearts. I then ironed freezer paper to the back of each block to stabblize them for signing. But, I needed additional blocks for people to sign (she had about 50 guests as well). So, I cut 6" squares of freezer paper and traced the heart shape on the paper side of the freezer paper and them ironed them onto 6" squares of the light fabric. I appliqued those hearts on the border. It worked great! I'm on my iPad and can't figure out how to attach a picture, I will try to add one later.
OH! The most important thing! I found some great pens for people to use to sign them. Pentel Gel Roller for Fabric. They write very smooth and I couldn't see any fading on my test samples-I did set the ink with a warm iron before washing. Only down side, the only come in blue, black and red.
Suze