Thanks for the suggestions of moleskin and even a smaller stack of post-its!!
Also, the comment about cutting with the ruler measurement marking a bit on the fabric instead of beyond the fabric. I learned that the hard way on my first big quilt that had numerous pieces per block--I ended up almost a 1/4 inch short on every single block so I had to cut them down and then the matching sub-seams were not even from block to block. When I thought about it, I realized that the way I placed the ruler on the fabric made the cut just a hair short; so that combined with the fabric "lost" in the seam I was bound to end up a bit short on the block size.