Are you looking at wood as a medium to just do a modern style box instead of plastic or are you after an "olde tyme" period look to the box? Or at least for the outside of the box?
I don't see many such cases in pictures or at the range for guns specifically. But there's lots of such kits for tools to use as inspiration. And there's no doubt that you're going to need to fit the internal separators for your own kit in any case. While I don't really have any pictures to show you because the ones I have are still packed away or were given away as Christmas presents I've done about a half dozen such "tool kits" in my time. The hard part is to make the kit light enough that when loaded up it won't produce a slipped disc.
There's a basic open top style "tote" tray type idea. Then there's the idea of something a bit more fancy with a drawer or two in the base that holds small parts. Something like this;
The next step up the ladder would be one similar in size and configuration to the basic tool box shown above but with one or two fold open upper covers. This isn't a common setup but it does have some old world examples. Again a drawer in the base to hold the small bits would be nice. Or perhaps a lift out insert. Here's two to look over;
Or if you're looking for something more traditional and classic and don't mind using two hands to carry it this old machinist's toolbox is done in the style of the old journeyman's tool box but to a smaller and more suitable size. Note it uses fairly "crafty" joinery with dovetails holding the sides together and frame and panel top. To keep the weight down you'd want to do something like this in cedar or pine and even then reduce the thickness of the wood to 1/2 inch. Note that in this case it uses lift out or sliding top trays for the small bits with the big pieces going below. That was the old world way.
Then there's always a deep top compartment variation on the classic three drawer tool kit. But in this case I'd likely make it a one or two drawer with the top compartment being deep enough to hold the bigger and bulky parts like the guns, powder flasks and loading stand.
Overall for materials for the old style tool boxes or field kits for flying my model airplanes I've been a big fan of 1/4 luan (mistakenly called mahogany) plywood for the main parts and 1/8 door skin luan plywood for any internal separators. It produces a light box so you don't get weighed down. But it wouldn't look right at all for the more classic machinist's tool chest shown above.
I must admit that I wouldn't mind a kit of some sort for the very same things. If you pick out a style you like I could probably be convinced to pop out a CAD plan for something suitable.
i also made the powder measure, knife, nipple pick and bullets. i did that antiqued finish on my brass bullet mold and handgun using some patina stuff that is like a strong acid i use for making stained glass. it's basically gun blue, i am out of gun blue so i used that stuff. it gives a nice finish on brass, and reminds me of color case hardening.
