What you will need:
Cardboard - lots of it!
Glue - a big bottle of white glue
Something to cut the cardboard - like a box cutter!
A straight-edge or ruler - to help make the cuts straight!
Step 1: Cutting the Cardboard
Score the pieces into sections that are8-8-7-7 ribs wide. Fold the cardboard on the scores, roll it up into a roughly equilateral triangle, with the two ends overlapping. (The image below shows a crosssection of what it looked like.) Glue the overlapping sections together and you should have a nice, strong triangular tube of cardboard.
Step 2: Start Constructing the Top.
You are going to glue your tubes from the previous step perpendicular to the ribs in the cardboard for the top. Leave some extra cardboard around the edges, because we are going to wrap that cardboard around the edges to finish it off. Glue the pieces with the double thick face down and just butt them up to one another.
You can see my tubes here all glued down and ready for the next step.
Step 3: Fill in the Bottom
Step 4: Finishing the Top
The two end sides are trimmed and scored so they just fold over the end face of the table, giving us some nice edges.
The sides are folded all the way around so they can be glued to the bottom of the table top. They should over lap by a good inch or two so we can glue them down nice and snug. Then trim them so they are flush with the angled edge of the table. In order to hold the sides in place while the glue dried, I created some makeshift clamps by cutting a notch in some spare cardboard that fit snugly around the piece.
When all this is dried, fit one last piece to cover the rest of the bottom. This doesn't need to be real fussy as it will not be visible once the table is put together.
Time to make some legs!
Step 5: Creating the Legs
Glue the leg pieces together and then glue the legs to the skirt. Build the whole assembly upside down so you get a nice flat 'top'. (Assuming your floor is relatively flat, that is!) I used a corner where the floor meets the wall to get a good right angle where I needed it.
Almost done now!
Step 6: Final Assembly
The final table turned out to be surprisingly robust. I can actually put quite a bit of weight on this without any problem. (Though, being cardboard, it will dent easily.)
You can finish this off by painting it or using decoupage or some other finish to make it more resistant to water and dirt from usage.