The Calibron 12-Block Puzzle

Originally copyrighted in 1932 by the son of Thomas Edison, this puzzle has been unavailable for over half a century. Can you assemble the 12 blocks into a single, solid rectangle? Just how easy a puzzle do you think an Edison would design?

The Calibron 12-Block Puzzle

12 pieces, about 6.5 inches square altogether
Difficulty:  (Extreme)
$25 each