This is for a 12" magnum
I'm hoping that I did this right and the box is around 1.8 cubes net tuned around 30hz.
the box is 24x16x17 outside dim. WIth 3/4 inch mdf.
The port is 14.5 x 2 and around 48 inches of port if I measured correctly.
Here are the sketchup pics
Look of box