I used (4) 3/4"Hx1/2"W rings and (2) 1/2"H circles for the top and bottom.
The total box height is 4". The total box width is 16.25". The inside diameter is 15.25" and the inside height is 3". The volume is 0.317 cu.ft.
The total volume is less than the recommended minimum but not by much.
The sub puts out plenty of base.
