Start from the lower end of the boom, and install and connect a tie rod diagonally toward the ceiling. The tie rod must have stiffness and form a very stable triangle with the boom. You can use any counter support. Generally, angle iron or steel bars with a diameter of 10mm or more are used. Some people also use main keels to reliably connect to the structure. The number and location should be determined based on structural mechanics calculations and on-site construction.