Originally Posted by bjeriann
What if you put a thin boarder around each block the thin all to the same size.
That's what I do. I call them 'equalizer strips', but make them wide enough so the blocks trim to more than 12½" (I use 13½" ). That way all the blocks have a bit added and it's much less obvious. I also make them the same color as the sashing so that they disappear.
Consider yourself lucky to have such slight variations. I've had some swaps where the blocks I got ranged from 11½" to 12¾". :D