The model T engine block was sand cast which is a technique thats been around for centuries. Most of a modern engine assembly starts this way still before a 6 axis cnc gets its grubby little mits on it. A CNC machine in three axis is easily homebuilt (zillions of tutorials on youtube) a precise lathe can be made from junkyard parts and cast from concrete (built one as a class project. Low chatter on a cement floor). That leaves a milling maching which can be build from the lathe and a drill press, also from a lathe. I can’t remember the name of the guy but he wrote a book series on builing a machine shop litterally starting with a bucket, sand, charcoal, and a looooot of scrap aluminium and pig iron. And that was in the 70s.
Edit: David Gingery