Every now and then, I run across an idea that is elegant. This is one such idea, and he makes it with a grinder and a welder!
A combination lock yard latch system:
I was impressed with the simplicity, and the reliability of this design. The only thing I'd change is I would plate it for rust prevention.
The relief rings would work better if they were cut on a lathe, and the slot would be smoother if they were milled. But the design is solid, and I like the way it works!
Maybe some other people can make one too, I think I will....