My friend is getting married soon and I would like to make a quilt for her.
I was thinking of cutting 5" squares of solid ivory fabric and have all the guests sign them with a fabric pen. There will be 35-40 guests total.

Is a 5" square large enough? Should it be larger? Should it be a rectangle instead? 4 x 6" maybe?

I was also wondering if anyone had some creative ideas on putting it together.

She's an earthy girl and I have some fabric in some taupe, beige and greens. I was thinking of alternating a signature block with a fabric block (so it's easy to do) - any other suggestions? I've quilted before but still consider myself a beginner, so I'm not up for a huge challenge!