Reference
Solar air heater
Hot air outlet port, 84mm of diameter
Mounting six wooden pieces on the back plate
Drilled 2mm holes where two screws go in
This was how I secured each wooden piece on the back plate: a square wooden piece, two C-clamps.
Four cold air intake ports
The size of port is 565.20 square mm. It’s made out of five circles whose diameter is 12mm, the biggest drill bit I have.
I spent 20,000 KRW for two glass plates, 510mm x 400mm, thickness 5 mm.