I came across some small cannons a while back built by Blackpowder-Cannons.com. They were small affairs, but sturdy, and could throw a cement filled soda can quite a ways. Then I ran across the proprietor's other projects and it all got interesting. The following picture is one of his soda can cannons... and only 300 bucks.
Then I ran across an old forum post of his showing off his replica miniature Hotchkiss revolving cannon, muzzleloader of course!
And here is a video of the Hotchkiss off his old youtube channel, cannonfab's channel
And he must get into restoring old cannons, here is one of his videos from his newest channel after restoring an old Maxim Nordenfelt gun from the Spanish American War. Looks like quite a handy guy.
I spent an enjoyable afternoon plinking with the thoroughly modern but heavy Walther P-38. About the only thing about the P-38 that isn't modern is that it is made out of steel instead of polymer. The double action/single action operation is on par with modern pistols... a round can be carried in the chamber with the hammer down safely, and being put into action by just pulling the trigger.
The P-38 simplified construction compared the German Army's previous handgun, the Luger P08. The Luger's parts were incredibly complicated and it took forever to build one. The P-38 halved the time, but it was still more complicated to build than the Allies sidearm, the Browning M1911.
This particular gun was built in 1945 by the Carl Walther plant in Zella-Mehlis. The numbers are mismatched, and this has been noticed in other Walther marked guns from 1945. The plant was captured by the Allies in April of '45, and you can imagine the workers cranking out guns while being bombed in the last days of the war.
The finish isn't bad for a late wartime gun, it has no import stamps but has some visible tooling marks. Shoots great, and it carries 8 shots plus one in the chamber. You could use this gun for self defense safely, but for concealed carry it is pretty heavy.