Room treatment panel for temporary or experimental purposes
4" pine 8mm cladding for less than £5 cut to 4'x2' and joined at centere of board with steel 90deg corner plates. Garden wire across corners tied to plates for strength but no weight. Two sheets of RS60 or similar either side of the central wired 'struts'. Staple cheap lining material to back and audio cloth to the front.
One 4x2 bass board costing very little and light enough to move around for positioning or temporary use.
Eat your heart out Heath Robinson