I did this and it turned out great!!! Sorry don't have a picture.
I know this is probably not the idea the OP is looking for, but I wanted to give this info for other people reading this thread. It is important to remember that the fabric squares must be cut very accurately and include a seam allowance. For example, if you want a 6" finished block, cut the squares 6 1/2". Use only high quality 100% cotton quilting fabric and think outside of the box. The squares don't have to be solid white. There are many beautifu fabrics that have a tone-on-tone design or a washed look. My squares were mottled-type pink, sort of a cloudy design.
The fabric squares have to be stabilized!!! Very important or they will just squish up when characters try to sign them. For my 6 1/2" squares, I cut 6" squares from freezer paper (the kind you find at the grocery store in rolls. I ironed the freezer paper to the back of the fabric squares, glossy side down. This will stick the to the fabric long enough to provide stability for the fabric when it is signed. It will pull off easily when you get home.
In addition to the paper backing, the squares need a hard surface underneath. I found a small (5x7) plastic clipboard and clipped a new fabric square for each character. I carried the squares and clipboard in a ziploc bag to keep them clean and ready to go.
I'm sure that you could find quilters in your area or online who would be able to provide the constructing and quilting to finish the work of art for you. I say "work of art" because I would only use this as a wall hanging. I would never put this amount of work into something that would require washing. The signatures just don't look as great after washing, especially the colors other than black.
Feel free to ask me any questions,
Lynda