Thimblebug: First your block is great, what a great center it will make. This is the way I understand Jabba, each "block" on the border will finish as 3inches then you have to add .5 inch for the seam allowances. So you have to make the center block divisable by 3 plus .5 inch. I know Jabba and Elizabrat check in regularly so if I'm wrong they will correct me.