Option 1
The first step is to measure the height of the room. Then, in the same length are cut the three profiles.

Calculate the width of the walls of the box.

If you are going to paste over his tiles, it is best to withstand the width times the width of the tile, then you do not have to cut it.
If you are going to putty and paint box, its size makes as little as possible.
Using a pencil, draw a square and a line on the floor, which will be mounted box given its size.

Drafted on the lines set and attach to the walls of the two guides. Mounting screws with plugs made inserted into the drilled holes in the wall. Checking vertical level of the building is made.

Cut a piece of drywall, which will serve as one of the walls of the box. This can be done with a hacksaw or jigsaw on the given size in advance. It immediately tighten screws to one of the established profiles.

Carefully measure out and cut the second strip of drywall.

The third profile is screwed to the inside of the installed drywall. It will serve as a rib structure.

It remains only to tie the second cut strip of drywall – and your box is ready!

Option 2
The difference with the first embodiment is that the boxes should have three walls, respectively, four metal guides. In other respects the principle of fabrication and installation of the same box as in the first embodiment.

If the duct must be large, the vertical guide are interconnected by two horizontal, which can be produced from scrap. This must be done to make the structure stiffness. The horizontal profiles are fixed to the floor and ceiling.

The side walls of the box are made equal to the width of all lines and rectangular structure checked the level and square.