Blast furnace

Blast furnace is used to produce Steel, the main ingredient of Steel tools. To create steel you require 4 Ore and 4 Charcoal.

It should be noted that there is a flaw in the model design that can result in workers (and any passing through the structure) getting trapped and eventually starving to death.

With 9 Blast furnaces set-up in a grid and 3 sides blocked off (to prevent all but workers access), 5-12 villagers will die a year (12-60+ with no sides blocked off)...