So most people on here have modified or are in the process of modifying their guitars. In all of the 17 pages of this topic, there's been maybe 5 attempts to build an amp or a cab. Because freight is so damned expensive to get a decent cabinet up here to Townsville in Nth Qld, Im thinking about building one myself.
Has anyone else on here done this, and if so, how did it turn out? I found somewhere else on the net some plans for a Marshall 1960a which I intend to model my cab out of. Im thinking about using Celestion Greenbacks 12" speakers and either covering it in a really loud coloured vinyl or possible have vinyl sprayed on to get that stucco hammertoney effect. I havent got a head for it as yet, so its not going to be a rushed project.
I figure I can get a cab second hand for about $700 AU, and probably an extra hundred or so for the freight. So, with the speakers retailing at $95 each, brand new, I should be able to build one and save a couple of hundred.
Well, to be honest , i thought about it, but i didnt have the time yet, its fairly easy, you build a wooden box with speaker holes, you wire the speakers depending on their impedance (you will probably want either a 16 ohm input or 2 8ohms, really depends a lot on the head you want to use and if you want to use one cab only or 2). Building the wood box should be the part that gives you the work, the rest its quite simple.

Hope this helped
I made 2 2x12s. One was oversized with offset speakers the other was slanted. I stacked them on top of one another. I guess you're supposed to have proper dimensions but I just made mine up and they sounded fine.
Cabs are easy to build if you make them easy to build.
You could do dovetails, rabbet the back, dado the front, recess the speakers, have flush-mount handles and all the fancy fine stuff or screw together six pieces of plywood and call it a day.
Of course the well-built one is going to be better but the slapped together cab will work, just not nearly as good.

In the end it's just down to your skill level.
..I was watching my death.