I can't remember where I found the more recent accompanying write up for this plan, but the original drawings and idea were from a 1937 magazine, I seem to remember it from somewhere. I know Popular Mechanics published a similar plan that I seem to remember including in a previous post.
This is an excellent little machine for the model making hobbyist who is not afraid of, and has the means to melt low temp. metals. Small metal parts, for all types of model construction, can be produced. The most challenging part is making the dies, but if you have the hobby machines to make metal models of engines, cars, trains, or planes, you can make the dies.
In the article the author had the melting temp. for Zamak at 1800*F, probably just a typo, I changed it to 800*F. Here are the details for Zamak from Google. This metal is ideal for this kind of work.
"These alloys are commonly referred to as Zamak alloys, which is an acronym for zinc, aluminum, magnesium and copper. Zinc alloys have a melting range of about 380-390°C (~ 725°F) although higher levels of aluminum can increase the melting point to as high as 480°C (~ 900°F)."
Here is the article, max out the "expand" for best view.
Zamak is a popular die casting metal. It is available in casting ingots as Zamak 2, and 3 among many others. If you pursue this neat little die casting machine, the author refers to Zamak 2 in the article. It has the highest strength and hardness of the Zamak family of metals and has good die casting characteristics. Melting temp. is actually 725*F. Here is a info. sheet on Zamak 2.