off by an inch is a bit much I agree. I used to swap signed quilt blocks all around the world long ago, before postage went up too much. Such fun and lovely quilts to be made up. Loved doing that.
and i've won a whole quilt of blocks in forums since then. twice at least. Two lovely quilts. all matched in size too.
we must learn what a 1/4 inch seam is and precise cutting and go from there. Until that is done, no swapping.
keep on trying though. it really is fun.

I should have mentioned most swaps stipulate the host will measure all blocks sent in to be swapped and would be returned to sender if not the correct size. This prevents any of these measurement problems.

Two different guilds--joined the "Bag Ladies" and the "Tinners". Same concept. You put your preferred fabrics in a container and specify what size block you want. Each month you get someone else's bag/tin and yours goes somewhere else. Other fabrics can be added by the block maker. At the end of 12 months there is The Big Reveal. I did my very best to make interesting, properly sized, well constructed blocks for the bags/tins that came my way. Sure wish the other members would have been as considerate about my bag/tin. They are still UFO's in my sewing room. Don't want to deal with the pain of wasted fabric or the headache of crappy blocks.