Yes, the small ones are just a tad small, so adding a border on them all around, centering the block, will make a bulky seam all around. What I need to add is mainly to just create the proper seam allowance on the outer edge. I don't mind fudging in 1/8" but if it's more than that I prefer to add fabric. I've added fabric on only 2 sides on one block, rather than 4 sides, to help with the seam situation and it laid flat ok.
I'm not keen on mug rugs. I prefer to put unused blocks in a pile. I've made a top that way, just sewing together odd blocks I've collected. You can add fabric to smaller size blocks by setting them on point, then cut the result to the proper size to fit what you are sewing. Even with only 4 blocks, by the time you set them on point, and add a border or two, you've arrived to a baby size quilt top. :-)
Last edited by givio; 11-26-2015 at 07:22 AM.