Sadly, as the grandson of carpenter, my woodworking skills are seriously lacking. The picture that I posted was from a member of our state forum and there were no others showing how it was built. I would imagine that it was screwed to wall studs with some serious lag screws.
If I were to try to tackle this, I think my goal would be to make it as lightweight as possible, while making it appear to be heavier duty than it is, but at the same time being structurally strong enough to handle being supported only by one end. I think I would build the inner structure out of 1”x2”s and skin it with some 1/4” plywood, except fir the end that will be mounted to the wall, I would probably use a piece of 3/4” plywood. That is just my thinking and I would likely suffer a failure or two along the way. I hope there are some better carpenters in the audience here. :)