This is a King Size bed, which is the same as 2 Twin Extra Longs, so that is what I made; for ease of getting in the house, and so that is can be used as 2 separate beds if the need ever arises.
3 4x8 sheets of 3/4" OSB
1 4x8 sheet of 1/4" plywood
20 1x3x12' furring strips. (If you hand pick the strips, you can get away with 8footers, I needed the extra length to avoid knots/splits, etc.)
Wood screws (I used 1" and 1 1/4")
2 magnetic cabinet clasps
Drill/Driver with bit for screws
Table Saw (or circular saw)
Miter Saw (helpful but not required)
I spent $84 on this project, but already had the sand paper, glue, stain, and 1/4" plywood.
In the pictures, the drop-down front is not shown, but it will cover the 2 storage openings in the front. Looking at the finished project, next time I would have just stained the inside and left the openings exposed.
Check out the DIY latex mattress that went on this frame: