From what I understand, those three companies (in general) make some really thick cabs. I would assume it's at least an inch of ply all the way around. The weight should give it away, Mesa and Orange cabs are heavy as hell, never lifted a Bogner cab personally, but I can guess from the weights of the two I have, they are fucking tanks.
I have actually been doing a lot of research on cabinet building in the past couple of days and found some really great info. check out
this thread for all of that information. The general consensus is that you should use birch plywood to build any cabinet, and it should be 3/4" thick or more. Bracing the inside of the box heavily, and make sure it's as air tight as humanly possible. Some people have even put insulation inside the cabinets. Supposedly that makes the cabs tighter and more defined. I haven't had any personal experience so I couldn't say if it does or not.
For basics, you should start with the size of the speakers going into the cabinet you want to build. The general rule is that there should be a minimum clearance of 1" around the speakers at all angles from anything else. So if you were making a very small 2x12 cabinet, then the baffle that the speakers sit in would actually be (2*12=24, +1" on all sides, so 4" inches total width-wise and 2" total height-wise) 28"x14", to allow 1" of space around both speakers. You can obviously allow more space, as seen with most cabinets made by Mesa, Marshall, Fender, Orange, etc. Keep in mind, that just like subwoofers for car stereo systems, guitar speakers need a certain amount of air space to operate at the optimum level. You can have the biggest 2x12 in the world, but the insides are designed much smaller than is perceived by looking at the outside, to allow for the correct air space.
Then, typically the back peice of the cabinet is anywhere from 3-7" from the driver of the speakers (the big ass magnet). So just go from there, it's actually painfully simple unless you want to get into tuning your cabinet as well, which if you play in a certain tuning ALL the time then having a tuned cabinet for that tuning would be immensely helpful in getting a killer tone. But tuning cabinets is like quantum physics to me...it's a LOT of information to measure and then process. Basically, anybody can build a cabinet that will do it's job. But it's when you get into tuning a custom cabinet that really makes the difference. Obviously Mesa doesn't have a cabinet for any specific tunings, otherwise there would be a shitload of models of each series to choose from. Mesa cabs sound great though, so that's goes to show that whatever dimensions you use will be fine.
Just make it big, make it thick, and don't use crap parts in it. And lots of acoustic sealant, or good 'ol silicone.
~e.a
