I made a disappearing 9 patch... after it was quilted I found two of the rectangles were back to front... while sewing it I found two then, so changed them around but didn't use my head and realise that there would be two more as the finished blocks are cut in half both ways... so of course there would have been four... such a shame but it could have been worse... they were near one end... imagine if they had been in the middle !!!