Build Gun

The Construction Tool is a placeholder name for a tool engineers can use to place buildings. It projects holograms showing where the building will be placed, and highlighting key features such as belt inputs and outputs and power sockets. It can also perform some sort of scan.

Mass Building
There are currently no systems in the game equivalent to blueprints (from Factorio) allowing for building multiple structures together. A blueprint system may be added post alpha.

Speculation
It is likely not an attainable item, but rather something engineers always have. Its scan may detect ores, as seen in the trailer.