Where can I get steel channel with a channel width of ~12mm to edge and support some 12mm (actually it measures nearer 11mm) plywood? Everything I can find seems to be wider. Depth isn't important, say 8 -
15mm, and about 2mm thickness would be fine.It needs to be steel so it's easily weldable. If the channel internal corners are a bit rounded I can sand the ply.
Cheers