I built a base for our CalKing last spring, and it's surprisingly easy. Here's the short recipe: You need a table saw or a really steady hand with a circular or jigsaw, a drill, a couple of sawhorses, and a helper. Materials are 2 sheets of 1/2 inch x 4 ft by 8 ft plywood, sanded on one side, 3 8 foot by 1 inch by 2 inch pieces of decent lumber, paint or stain and finish (Future Floor acrylic works really, really well, and is non-toxic) screws, L braces, flat nail plates, a tape measure and a marking instrument (I use a woodless graphite pencil.) A king is 76 inches by 80, so you will be cutting two chunks of the sanded plywood that are 76 x 40. From one piece of remainder you need to cut a piece that is 72 inches long, and 8 inches tall. (If you want your bed to be taller than 8.5 inches + height of mattress (and maybe box) you will need another piece of 1/2 inch ply, and will need to cut it to your chosen height.) From the rest, cut 3 pieces of 48 inch wide by 8 inches tall. In the center of these short pieces, cut a groove a half inch wide to the center of the board. Paint everything now, if you're painting, staining, etc. Now slot the short boards on the long one, like Lincoln logs. This is the support. Use L braces and screws to secure the support together and to keep it from being wobbly. Now lay the two big chunks on top of the support, centering them. Join the big chunks to the support with L braces, having your helper keep the plates aligned and steady. Then join the plates together with a couple of flat nail plates and screws. Finally, cut the 1x2 to fit the edges and foot of the support plate, screwing them to the outside of the plate. These will hold the mattress in place on the platform. More detail to follow...

Oh gosh I have NO idea, but I love this bed, too. AND your comments! Coolest gal I know!

Nice lookiing.  You could merely hang the chunk of fence (or whatever) on wall to simulate headboard vs attaching to bed platform. I just saw this pattern in a fence but sorry, don;t remember where or what style.   Gothic, victorian?

Okay, you're gonna think I'm crazy, but I know I've seen fencing that looks very similar to that headboard. I've always wanted to try making a headboard out of a pre-made fence panel. Very cost effective!

I bet Creede could help you out; he's written about building your own modern bed before.