So, I think I decided on using two 12" Celestion Rocket 50 speakers, rated at 8 ohms a piece. I'm gonna wire them in series, probably, as my amp is 8 ohms and I'm going to be using this cab when I play in the privacy of my home or dorm room at college in the fall. That way i can have a louder volume tone from my marshall dsl 50, but at quieter volumes. Does this sound right to everyone?

Second, how do I go about building the box? What kind of wood should I use? What thicknesses? I want the box to be about as wide and deep as my amp is, so I believe that is 30 inches wide by 9 inches deep. However, how tall should it be? It will obviously have to be at least 15 inches tall, but what is the smallest I can make it?

Basically, any random advice/help would be awesome, as this is my first project for building a cabinet! Thanks in advance!
On second though, I may use eminence Patriot the Copperhead 10" speakers instead. They are 75 watt and still 8 ohms, so hopefully they'll do the job the same but require a smaller box? How does everyone feel about these speakers? Or any other recommendations?

I'm basically trying to make the cheapest possible decent sounding 2x12 cabinet.
^Theres a huge thread up at the top, and I think a bunch of questions are answered in there
Try reading that first.
And look into some Eminence speakers before you jump for the Celestions. They're cheaper, and IMO, just as good if not better.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
I am looking at the Eminence speakers as well. That will basically just come down to whatever mood I am in when i order the speakers, i think :-)

However, I am looking at any specific info I can get on my situation. I want the smallest possible, closed back 2x12 cabinet. I guess I'm basically just looking for the exact sizes I need to cut the box to be, and what size holes for the speakers. I can do all the wiring and choosing for the speakers myself. Thanks!
For open back cabs, I don't think dimensions are all that important...
From what I remember from that sticky, you'll want wierd dimensions, in odd numbers or so...
You can always measure an existing cab too.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
I am currently making one. I've posted some blueprints.. you could just follow me along as I build mine. Or just walk through mine when I am completed and build yours then. I'm going to start building the frame and panels this week