I have to make a lightweight screen panel, 48" x 16", as thin as possible commensurate with absolute rigidity. It will be hinged on one long side and attached to a much larger solid wall-mounted board.
For the panel I suppose I could use 18mm chipboard or similar, but the weight would be prohibitive. A wooden frame with a thin sheet covering would, in my experience, be difficult to make absolutely flat, and would be prone to warping. So I'm considering a metal frame, say square-section aluminium, with perhaps a foamcore board surface.
What is the best way of fastening square aluminium tube to itself at the corners? Does anyone make a right-angled corner piece/plug especially for this purpose? I've searched around of course but not found anything yet.
Alternatively, what other materials (plastic framing? Solid plastic sheeting?) might be suitable?
Many thanks.