This floating desk hangs in my daughters room. Her vintage four poster bed from our previous home didn't fit well into this space. It had a lot of sentimental value to both of us as it was a gift from her Grandparents. We couldn't get rid of it so we re-purposed it into this desk.
First, the four posts were removed (and saved for another project). Then, we took the headboard and the foot board and screwed them together on a 90 degree angle. Then came little caulk in the seam, a little putty over the nail holes, and a coat of white paint. I picked up two large white brackets from Home Depot and mounted the desk into the studs.
Her room is tight on space so a floating desk was a great design solution.