It is every person who has been saved. If you are saved then you have been employed by God to be a carpenter in the construction of His building. The ideal suggested is that every believer is to be working in the building of the Church. Each time a person is saved, the Church is being built. Each time you witness to someone and they receive Christ, the Church is being built.
Every believer is to be a heavenly carpenter.
Each of us is to be involved in the work of getting people saved. Every Christian should pick up their spiritual hammer and saw and go to work. In construction terms, there is what is called the dead load and the live load. The dead load is the total weight of the building and all its parts. The live load is the weight of the furniture, equipment, occupants, etc., in the building.