After digging through my collection of scrap building materials, I've revised my plan for mounting four concentrators in a box together down to three. It turns out that I've got at least twelve 2.4m (8') lengths of 4x2" pine, but only one length that's over 3m, so removing one concentrator brings with width down to 2.25m and saves me from needing extra joins or materials.

So for the three-concentrator panel, the general parts list is as follows:

• 2.4m 4x2" pine x8
• Corflute, or wooden slats, for sides x? - should have plenty of either already.
• 44gal drum x2
• 1,500x750mm windows in aluminium frames x3
• 1/2" threaded steel pipe, 1,100mm long x1
• 1/2" threaded steel pipe, 1,300mm long x2
• 1/2" threaded steel pipe, approx. 500mm long (depending on elbow joint) x2
• 1/2" steel pipe elbow fitting, female-female x4
• 1/2" gate valve x1
• Tank x1
• Connecting hose for tank and associated fittings for gate valve
• Chrome vinyl wrap, 1,520mm wide x1,500mm
• Adheasive foam seal material x12m
• Galvanised steel sheet metal for collector panels, 900x290mm x3
• Matt black or blackboard paint for collector panels
• Nuts, bolts, screws, nails, etc.
• OPTIONAL: Ceiling insulation material (try adding this after completion)

Pine lengths will be cut as follows:

• 2.25m x4 (4x 0.15m left-over)
• 1.5m x4 (4x 0.9m left-over)
• 0.35m x4 (from 2x 0.9m, 2x 0.2m left-over)

To Buy:

• Windows
• 1/2" threaded steel pipes
• 1/2" steel pipe elbow fittings
• Chrome vinyl wrap
• Adheasive foam seal material

The most important parts which I don't already have are the windows, because they set the dimensions for everything else (and I'm not entirely confident in the dimensions stated in the advertisement). So before buying/building anything else, my first task is to bite the bullet and buy those.