Mickey,
I have a few pairs of aluminum valve covers, They're about three inches high and three wide and as long as a Chevy cylinder head, but you could easily cut one down to length and join the two shortened halves with JB Weld, or I could do it for you if you gave me the length that you want.
I have some ol'skool finned Cal Custon covers from my Corvette, some signature-style Edlebrocks from my V8 Volkswagen panel, and some older Mickey Thompson covers from a friend.
You're welcome to make an "aluminum box" out of any of them. Just lemme know, OK?
Forum Prick
Oh, hey, I just noticed something . . . if you want to go rounded, you could use one of those cast aluminum nine hole steering wheel adapters/mounts. Hog out the splines and stuff for the shifter to poke through and move freely, grab up a large V8 juice can and trim the top to open for the shifter and drill around the remaining lip to accept the nine bolts that hold the steering wheel adapter on in an up-side-down position, then trim the sides of the can into a saddle configuration to fit the tunnel. Krinkle black finish on the juice can, sand cast finish on the opened up adapter.
A nice vinyl/leather boot or the rubber boot from a 911 and it would look pretty neat and semi-factory racing in a strong way.
I might not be clear, but I could whip together a mock-up and photograph it if you're at all interested.