Tim, I would suggest you look at pressed galvanised steel electrical enclosures as one option. Just as strong as a cast Hammond style enclosure, but much cheaper. They come in a whole range of sizes too.
Something like this, at 12"x12"x2":
http://www.ebay.co.uk/itm/Galvanised-Steel-Adaptable-Mounting-Box-Electrical-Enclosure-300-x-300-x-50mm-/290709911420?hash=item43afa9377cAlternatively, if you want a long strip style enclosue for the front of a pedal board, you could use 50mmx50mm (2"x2") galvanised electrical trunking and lid. You can cut it to your exact length, fit the caps to the ends, and mount the switches in a row.
Like this:
http://www.ebay.co.uk/itm/50mm-Steel-Galvanised-Cable-Trunking-x-3-Meter-PT50-Q2-/321992112339Note this is for a three metre length - enough for several loopers!
Any electrical wholesalers will stock it, and if you know any electricians, they might have offcuts for cheap or free.
I built a looper strip for a friend's pedalboard out of this stuff a couple of years ago, and it's still going strong.
Worth a look.