Position the foam board with the long edges on the sides. Cut two horizontal strips each 11 3/4 inches long, and cut each strip into 6 3/4 inches wide. I store fabric 3 yards or greater on these pieces. Sometimes I will put several fabrics that I matched for a quilt on a single board; then I fold down each fabric into a 45 degree triangle and put two pins on either side of each piece to hold it.
Cut the remaining strip into rectangles 4 inches by 6 1/2 inches; I use this for fat quarters (two per card) or fabric that is less than 3 yards. The 11 3/4 inch height of the larger cards allows you to out them into a stanard bookshelf vertically. Then I put the smaller boards in frony of the larger boards. Besides cleaning up the piles of fabrics, I am always ready to unpin and immediately cut the fabric. I end up with neat fabric arranged according to the color spectrum -- and I can avoid buying stuff I already have.
If I have larger lengths of fabric bought for a quilt, I put them on the large boards and tie a ribbon around the set of boards.
I cut the foam board with a Logan matcutter. There are several at different prices.