Illustrated Book on Tree Houses
This is a black and white illustrated book on tree houses of almost impossible designs, of a Rube Goldberg or Dr. Seuss complexity, full of multiple levels, ropes, block and tackles, ladders, wooden shingles, stove pipes, etc. I remember the illustrations looked like Erik Blegvad’s style of crosshatching, but it may not be him. Very fun book I got from the church library when I was ten, so it would date from the 1960’s.