I searched for a bed like this but didn't find anything I liked that was well-built and affordable. So, I'm building this one out of solid wood for about $450. (Except I had to buy a new miter saw, because my old one was stolen out of my garage about two years ago, so that was another $250.)
Edit:
You'll need the Measure It addon installed and enabled to see the dimensions. The gray boards are the blank stock pieces I bought. It's in inches, because I'm a stupid American.
Here's a screenshot of the blender file:
Edit 2:
I have most of the pieces cut to size. I've already made a small mistake, but it wouldn't be my project if I didn't. Nothing a little wood filler won't fix. The side walls of the headboard with the angles I'll need to cut with my circular saw. Or, maybe I could do it like this. I'm not sure my table saw is big enough. (Also, it was either woodworker or piano player for this guy, I think he made the right choice.)
Edit 3:
I'm stuck waiting for the Vevor pocket hole jig I ordered, and the bed rail hardware. I didn't get the Kreg, because it's plastic and more expensive than the more versatile Vevor jig.
I don't think his design has the box spring sitting on the sides of the 2x6s, or else the legs of the headboard would get in the way of it sitting on the top most crossing board. The center board seems to be recessed, which leads me to believe that the small blocks on the header board and some smaller boards on the inside of the side boards are holding the box spring, which if the main side boards flex or bow the box spring will fall past.
I'm a cabinetmaker by trade, so I'm thinking in terms of what I've seen go wrong in builds with long, unsupported boards. But like I said, maybe the angle makes it look like the inner supports are super thin.