I used 250mm galvanised cable tray for all cable and pipes in the engine compartment(semi trad) and it made fitting out very easy. Also proved useful for mounting the many bits and pieces like battery isolating switches, fuses, valves etc.
I managed to buy a few 3m lengths for a few pounds from the local army surplus store - they are quite expensive new.
I got my shell builder to weld mounting angles all around the engine compartment otherwise not sure how you would mount the trays securely.
Paul