I simplified the build a bit because I don't nearly have all the tools William have. I must also submit that I could simply not afford plywood and settled on 18mm MDF instead.
This build came about when we emigrated and needless to say, money is an issue and we get family visits from time to time and it is not cool to let your wife's parents sleep on a matress on the floor.
All the materials used are readily available at your local hardware store. I also had the MDF cut at the hardware store to simplify the build (and I also do not have the tools or space to cut it).
UPDATE: Unfortunately, my better half decided that she want to upgrade our bedroom suite and we decided that our current furniture will move to the spare room. Needless to say, no more bed to build. I will still put some Sketchup files and jpg's up here if anyone would be interested in building this box bed.
Step 1: Step 1 - Research
I also decided to make two bedside tables and finish everything in the same style. I first decided on the materials to use and then I made some rough drawings in Sketchup. (See the images below)
The completed drawing with all the components can be seen in the first picture. Please note that the pictures does not have any support drawn in so you will need to add your own supports where you think they are needed.