My bed frame is built from birch plywood, with 2×3 stringers underneath. It’s sectioned into thirds with hinges so that I can taco it up and get more bed space if needed. It’s slightly smaller in dimension than a twin-size mattress.
The holes in the side rails allow me to lift the bed and support it on 1″ aluminum dowel pins. I can stuff skis and other crap in the space underneath, and still have decent headroom. It’s helpful for weekend trips, and easily converted back to full headroom for weekday living. In retrospect, I should’ve raised the side rails a bit so I could fit 10 gallon totes under the bed, but this works fine for most of my needs, and the headroom is still great.