I'm starting to make preparations for the arrival of my first trio. (Tamuk) I'm wanting to build the cages myself. I'm thinking with 2x4s, 2x2s, and 12g wire. I'm wanting it to be one large cage with wire dividers so that the buck will be able to see his does. I'm thinking put the buck in the center? I'm unsure about sizing. It will be an outdoor cage, so I'm also looking for ideas as far weather proofing. I live in SW Missouri. I'm also planning on building a grow out hutch in the very near future, but want to get the cage built first. Thanks for any insights!
I like to keep my bucks separated from other rabbits with solid dividers between cages because many of them spray when they can see does, or another buck. This makes it hard to keep the rabbits clean....ick.

Sometimes they'll still spray, but at least it doesn't cover the other rabbits if there's a divider. They'll still know there's a doe on the other side.

Solid dividers also prevent or at least reduce barbering, fighting, and/or nipping through the wire.
When assembling, make sure to put the 1 x 1/2" bottom wire "right side up," meaning having the wire spaced at 1/2" intervals facing up toward the rabbit, so the rabbit's feet are well-supported, to reduce problems with sore hocks. Galvanized wire will last longer than non-galvanized, although all wire eventually seems to corrode under the assault of rabbit urine.
I avoid, to the greatest extent possible, solid supports underneath the cage wire bottom. Anything solid will collect hair, poo and urine, making hygiene challenging, especially when things freeze in the winter.
As far as weather proofing, rabbits just need to be protected form wind and precipitation. (Direct sun doesn't usually do them any favors, either.) Solid roof and sides, or sides that hinge up or down depending on weather conditions, will go a long way. I avoid tarps because where we live it's often windy, and a flapping tarp can stress the rabbits.