There are several stages in the building of a set and, for a large project, many people may be needed. The set designer has to design the set. A model will be built to show what the set will look like. Drawings are made.
The technical director or production manager will look at the designs and decide whether they are what he wants and whether there is enough money to built it. Then a master carpenter will tell the people who work for him what they have to do. There will be carpenters, plasterers, welders, painters and, perhaps, several other craftsmen.