Look at the circled areas... The diagonal line has been bent, bent upwards on the top one and bent downwards on the bottom one. Its very slight, thats why at first glance you don't notice it.
Actually, the top and bottom pieces are exactly the same. The explaination is that there is a difference in slope between the large triangle and small triangle. When re-arranged, the difference in slope is slight, but yields enough for a whole empty unit. The graph adds to the illusion. Good job!
You probably put more effort into it than anyone else............Wasted effort maybe, but still effort:grinthumb
Somethings not right, I printed it out cut it out really carefully and it fits. I took lots of care Its a mad world
Hey, never mind that, there is a way of folding a strip of paper in such a way that it has only one surface....
Flip one side over and attach the ends. You can also make a solid with one side the same way. LNCPapa