Hey Tom!
Just like Chris said in his post below -
K.I.S.S = Keep It Simple Silly (or Stupid)
This is meant as a reminder to oneself, so don't take it as HH calling your silly or stupid 
I usually use "Keep it simple, stupid" instead of "silly." Mostly because I'm talking to myself when I say it. I'm the world's worst for getting too detailed, going overboard, etc... I constantly have to repeat KISS to myself.
Chris - all side pieces are sandwiched between the top & bottom pieces with the two end walls sandwiched between the front & back walls. The two front pieces (top & bottom) that go the length of the cage are temporary, used as butts for face frame positioning. The vertical support will be slightly more forward once face frame is on.
My philosophy for the walls being set between top/bottom was to give the most support to the top and avoid stress on the screws if the walls were to have been screwed into the thickness of the top/bottom pieces. This was important to me since I'll be stacking 4 high.
Chris, you made a good point about racking (twisting/contorting). First thing I did was screw/glue one side wall to the back wall & then did the same to the other side wall. I then secured the top onto the back wall first, and then the two side walls. It wasn't much out of square and went good.
I had the most fun getting the bottom sheet squared & secured. Of course, I had flipped the cage over in order to do it but I had to torque & tweak things a tad to get it shored up. I'd a had a fit if I hadn't paid close attention to the squareness of all my cuts while cutting my pieces. But me, my Swanson straight edge, framing square, circular saw & $100 Ryobi table saw made it. Oh, and I used a router for the vent slots.
Tom, for what you're looking for - a permanent but mobile cage - you're going to have to sacrifice somewhere. I'd say my cage weighs somewhere around 100lbs or a tad more. With a set of furniture dollies (or even hand trucks) underneath it you can wheel it just about anywhere you want, except mine would have to be turned on it's side to fit through a typical doorway. Like Chris mentioned earlier, the room it will be kept in & the cage's maneuverability is what you have to watch out for. I could put my cage in a room at the end of a hallway but couldn't make the turn into a side room in most hallways.
Thanks for the compliments, fellas! I appreciate it. Good timing, too, Tom. I had just came inside from getting ready to stain my cage and took a break to check the forum when I saw your thread. Those are the first & only pics I've taken of it. I usually try to document construction but had to get a move on this thing. I'll keep ya'll updated.
Take care!
Mike
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Due to political correctness run amuck,
this ol' hillbilly is now referred to as an:
Appalachian American

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