I built a few wooden cases, they all got sold after a while as others wanted them more than I did. Solid wooden cases are generally pretty heavy.
Start with a Plano All Weather gun case, and go from there. It's probably the most versatile case I ever bought.
They are $69 at Amazon.
Once you have it, pull the bottom foam out and start doing some measuring.
Then go to the local building supply store and get one of the laminated tabletops about 1/2" and some 1/2"" x 3" x 36" poplar and oak for the dividers.
Lay the gun out with accessories and develop a layout for the dividers.
As you build out the box cover the bottom and dividers with the fabric of your choice and fit everything as you go. It's a lot easier to cover the pieces and then do the assembly than to get a good fit with the fabric after it's assembled.
I have two different trays for this case, one for the Citori Plus combo, and the other is setup for an 1100 and 4 barrels.
The finished case is heavy, but not as heavy as an Americase. Mine has been from the east coast to Tucson 10 times or more and the airline hasn't been able to break it yet.