I have in the past built up a number of subs (sealed for car use, isobaric ported for car use, ported for home use etc), and am comfortable doing so.
I am in the middle of finishing my basement, including a space for HT. The project, in addition to travel for work, had me too busy to truly DIY it this time. I met a local woodworker last year, and know folks that have used him before. One other AC member I am aware of also has.
This was my first project with him. He has a complete woodworking shop, and was able to pull this sub together for me in less than a week! Prices were reasonable too.
The design came from a conversation of the distributor of the Mach 5 Audio MAW-12 woofers I am using. I drew up the sketch, and advised of what bracing, volume and port I wanted etc. He took my design, and created the sawdust, and I picked it up this AM.
It will use a pair of 12 inch woofers, 4 cubic feet net, tuned to 22Hz with a 2 inch slot port.
Pics below.






One last one to give a sense of the scale. I am 5'8. This entire sub will be buried in a wall in the basement, and will fire through a grill.

Huge thanks to Jeff. If you are in the Toronto area and want a sub or speaker built, I am telling you this is your guy. Great to work with, reasonable pricing, and will custom build it however you want.