For racking strength, I added a piece of 3/4-inch plywood for the upper back, and ripped a narrower width of 3/4-inch plywood and installed it at the bottom. Then I stood the cabinet up, centered it on the wall, and screwed it into place.
The bed platform starts with a 6 3/8-inch-deep plywood box. When building the box, I joined the sides to the head and foot to cover the plywood edges so the only time the edges are visible is when the bed is down.
For strength, I built the bed platform with a 3/4-inch-plywood bottom. The two plywood pieces fit inside the sides and I pocket-screwed them in place.
I nailed 1 1/2-inch by 1 1/2-inch strips along the inside edges of the platform, and then I screwed the slats to the bottom between the edge strips on 10-inch centers.
To install the fold-down feet, I located and drilled holes in the outside end of the bed according to the manufacturer’s instructions.
Because the edges of the platform are exposed when the bed is folded down, I covered them with 3/4-inch by 3/4-inch-thick pieces of solid-wood trim.
To attach the hinge hardware, I started by drilling holes and attaching the bracket to the platform.
I clamped the paper template, provided by the hardware manufacturer, to the sides of the cabinet.As I drilled the holes, I took care not to blow out the plywood veneer on the outside.
Because I was working by myself, I clamped temporary legs to the platform to support it while I lined up the bolts to join the platform to the cabinet.
The pistons that help drop and lift the bed are held with a metal band in just the right position to fit on the bracket with the bed partially open. It helps to have one person hold the bed in position while the other attaches the pistons.