The 12" golds work best apparently in cabs of 90 to 205 litres. WxHxD x .61 or convert cubic inches to litres on line. Mine ended up an interior size of approx 125 litres after calculating in driver and bracing. 38" T x 16 x 13.75. 1" Baltic Birch. This is apparently a favourable size.
I am now going through porting and tunning. I am lucky enough to have professional help with this stage of the build. Correctly tuned, this cabinet should get me down to about 33hz which is very good.
I did not mitre I used but joints and re veneered the tops and bottoms to cover the end grain. My finished product will resemble the DeVore Fidelity Orangutan 0/96
https://www.google.com/search?q=arangutan+speakers&oq=arangutan+speakers&aqs=chrome..69i57j0...:
This is a fairly simple design to build. I have not built Cabinets before but do have solid basic wood working skills.
I would be happy to answer any questions you have about my process or tricks I learned along the way. I have never actually heard Tannoys so am really looking forward to it. I will post my impressions when I get there.
Cheers. Paul