We had a fun book in the lab a few weeks ago.  Contemporary Farmhouses: Flexiplan 71240 was published by the University of Illinois Agricultural Experiment Station in 1956.  You’ll notice from the photo that the book has comb bindings on both sides.

The first section of the book discusses construction and planning issues.

The second section is the Flexiplan.

The two comb bindings allow the reader to mix and match pages to create different houseplans.  Here, for example, is Plan A1.

Turn a few pages on the left and the right and you get Plan M7.

Pretty cool, don’t you think?