When it came time to build these, I had purchased a pair of HPD 315's from England. I looked and looked for a cabinet design, and found fairly limited information available. So I decided I wanted 150 liter bass-relief cabinets, but I wanted them heavy. I didn't have the tools or the space then, so I had a company in Philidelphia build them for me. They are 3/4" MDF overlaid with 1 1/8" MDF, and weigh in at 192 lbs. each, without crossovers or drivers.
They have turned out to be magnificient performers, excellent partners to get old and die with, and I will do just that!
Nice talking to you, enjoy,
Dan