I like any style and size of block, as well. Each set of 4 blocks (don't forget to make a 5th block to keep for your own quilt) should be the same block and size. I made 3 sets that were 12 1/2 and 2 sets that were 9 1/2". I didn't make any 6 1/2 blocks so I hope others will because I like the diversity of blocks for this quilt. All 3 sizes can be worked into a quilt. The individual quilter may need to add additional varying sized blocks when they receive their swap blocks to square up the quilt but that's part of the fun about adding more personal touches to your quilt. So...just create what you want and we will love them, I'm sure.