How do I assemble an IKEA under-bed storage box?

[Hantor]

I bought a couple of IKEA under-bed drawers secondhand, but the previous owner took them apart down to the last screw to make them easier to transport. Now I’m sitting in front of a mountain of boards and hardware, with absolutely no idea which part goes where. My attempts to put them together intuitively led to me mixing up the rails and nearly stripping the threads on the particleboard.