On the large unit you may need to add a front board to help with airflow as even the 200 mm sealey fan can struggle to empty the whole booth.

But at the size 2 or more students can paint at the same time. (Not Spraying).

Smaller Version Using 6mm Plywood. Vent Hole is 100mm. and will fit a B&Q bathroom extractor Or a computer fan and some flexible pipe.

Finally assembly Tips:-

You will notice my style of manufacture throughout many of the Boxford projects this includes:- Size for thickness machining of all holes in wood and fibreboard and size for thickness finger joints with no allowance for cutter diameter. This means that if a piece is to be inserted into a hole the tang will be exactly the same size as the hole and the hole will have radii at the corners. This causes the corners to bind up on the board as it is inserted creating an interference fit that will hold the work whilst the glue dries. Some projects are serviceable on assembly with the glue serving to make the joint permanent.

The must buy tool you will need to assemble these plans easily is a rubber hammer, they are available from most woodworking suppliers for less then £5.

The hammer will allow you to hit directly on the edge of the board without damaging it as you bang pieces into holes and hammer finger joints together. You may need some cramps to hold some joints but most will hold just on hammering together.

Try to work on opposing sides so that the hammering keeps joints from springing apart the more you do you will find this method of assembly remarkably easy.