I have been in two swaps. One with 18" blocks and the other with 8" blocks. Funny part is that everyone came through with the 81 8" blocks and only 2 of us did the 18". Trouble with the 8" is there were a couple of the ladies that didn't understand that 8" was finished size, so there was no 1/4" seam allowance on their blocks. I ended up squaring all of the blocks to 8" and putting them together with sashing. It worked ok, but would have been better the right size.