I was thinking that the ideal enclosure would probably be an old PC power supply, built in fan, many also have a built in on/off switch and have sufficient ventilation to keep a 500 watt power supply cool.
This is the company in England that told me their board is capable of two transducers with a 45 min on cycle.
http://www.ebay.com.au/itm/161668556182?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Hope that helps.
