This one has been in the shop since I moved in. It was an article from a magazine.
The bottom is installed in the picture and slides forward to put in the fine filter.
Then the bottom is moved in the opposite direction and two coarse, standard fiberglass
furnace filters are installed. Squirrel cage blower was from Grainger I believe. It is shown
without any filters installed since I was changing them when the picture was taken.
This is fairly heavy but it is supported on 3 trusses so not too much load on any one.
First picture is the outlet and the second is the inlet. You can see two slots that open
from the bottom when the lower panel is moved forward.