j-bird posted an entire pistol box making tutorial in June, 2007 titled
"My New ‘51 Navy Display Case!".
It documents how he made his 2nd "improved" pistol box, and contains many useful hints for anyone that's considering to build one.
Here's another thread that offers a simpler method of assembling a pistol box:
I don't have any clue to what they would be worth. But I would think that their current value would be linked to how much they originally cost or what the owner paid for them taking into consideration how long ago that was and adjusting for inflation. So the OP would know more about their relative value, just like with any used collectible guns on the market. Can the OP supply any information about their original cost and when they were made? Do they have brass frames?
The fact that it's a consecutive pair may add a little more value although that could also dampen interest from those prospective buyers that might only be interested in purchasing one of them. So however unlikely, each might be worth more being sold as a single than together as a pair.