I have started the build about two weeks ago but only now got around to writing this post.
Important disclaimer! My build process is NOT according to Bill's plan. I chose to start with the speakers baffle and work my build around it.
Also, because this cab is going to be covered with Tolex, I opted on completely separate back panels, as I think it will make the covering easier (no visible seams..)
So, Here are the baffles being reinforced with rings of 1/2" ply:

The joined baffle is glued to the bottom panel:
BTW, I'm using the Gorila PU glue seen on the right. Great stuff.

Top & bottom panels attached:

A mockup handle and driver are placed to determine the handle's location with good clearance from each other:

The first side panel is attached:

And the cab is ready for Tolex'ing..

As to the metal corner covers, I am using the regular square corner ones but need to re-shape the front four to match the cab's 8 deg. slope..
So I fabricated this metal jig which has the correct slope and rounded the edges to match the edges of the cab:

The square corner is secured to the appropriate corner and hammered on top of a piece of hard wood to take the shape of the jig:

And a dedicated 8 deg. corner cover is born (they will get another coat of black paint):

Now waiting for the purple Tolex to arrive..
