Welcome to the site. I have built my own gun cabnit but no plans. Just played it by ear. I like cabnits better than safes, seems this country is in one hell of an uproar over everything anymore. I took a different attitude and taught my kids about guns. Would send you a photo but haven't re-done it yet since my house burned.
Just keep in mind, your building a box to keep your guns in. Take it from there.
If you want to properly preserve velvet antlers, you will have to inject & brush them with formaldehyde or some of the new less toxic chemicals (4 in 1 solution works great as does Knobloch's antler in velvet tan) as its easier to use however, both will work.
First, using rubber gloves take a razor blade and make small incisions at the tips of all points about 1/8". Next hang the antlers upside down, allowing the blood to drain. Starting at the bases inject the solution into the...