this is only my 2nd instructible
Step 1: Preparing the Frame
Step 2: Legs and Support
these are mostly smooth, but it's still a good idea to sand everything once. use a nail gun to attach them to the frame. add a strip in the middle for support.
Step 3: The Top Boards
I found a few more discarded boards at the recycling centre, some didn't exactly match but that didn't bother me. though I was careful to pick out boards that were of similar height (when laid out). I cut the boards (length and breadth, measure twice and cut once - I made quite a few errors here and had to redo stuff) using a circular saw and used a planer for levelling.
use an electric drill to join the top boards to the frame. use an orbital sander to get the finish you're looking for. honestly, this should be the part of the project that takes most of your time. it can get boring but the finished look depends on the time you put in here.