"The Gasoline Engine" by B.P. Warwick
For the engine enthusiast this old manual (1898) has some nice documentation of the early gasoline engine. Warwick, himself the inventor of a small early type, covers the different types of engines available at the time with lots of information on their construction. This would be of interest to the modeler building those early engines or anyone interested in the development of the early gasoline engine.
The download is available on my Books - Free Downloads page. # 26 - 11 MB - pdf
"How To Make A Folding Machine For Sheet Metal" By Rob Hitchings
This little manual has been around the web ever since http://www.fastonline.org/ uploaded most of the ITDG (Intermediate Technology Development Group) workshop manuals many years ago. There are 10 that I am aware of and I have a handful in paper and another handful in digital download. This one gives good instruction on the construction of a nice sheet metal folding machine. Welding equipment is necessary.
Other manuals include a pipe bending machine, metal cutting shears, treadle powered wood lathe. foot operated drill press, hand operated hole punch, slip roll machine and others.
Download "How To Make A Folding Machine For Sheet Metal" on my Books - Free Downloads page. # 27 - 2 MB - pdf