Egged on by my meta-friends on DIYAUDIO I ordered the Thor components from Madisound in Wisconsin.  Then it got too cold to cut MDF over the winter so I spent the time figuring out how to work with Martin King's MATHCAD speaker design program, and plunged into work.  Scott suggested a cabinet 40 inches tall, 7.5 deep and 18.5 wide.  with a 3 inch diameter, 5 inch long port.  About 5,500 cubic inches.  A mass loaded quarter wave design.

I decided to play with the prism a bit choosing a beveled design which was 17.25 inches across the back, sidewalls 7.5" and a rhombus based upon a pair of 30-60-90 triangles.  The front baffle would be 9 inches across -- about the same as the D'Appolito design.  The cubes were slightly greater had I been able to figure out how to bevel the top of the cabinet, but close enough for government work.  This is a conceptual drawing from Solidworks.

Using Martin's MathCAD program I came up with what appears to be a pretty decent forecast of performance.

Well, here's the work in progress.  The welding tanks belong to one of my sons.