I built one, but the pics are probably too big for the bb. The legs are 2 2x4s bolted together, x 2. The top is an old piece of pine, about 6 inches wide and screwed into each 2x4 in each leg. Another 2x4 is 8 or 9 inches from the bottom (it is above the electric heater) with 2 bolts in each side, for support to the legs. Feet can be cut from a wider piece of pine; I wanted to have semicircles, but I couldn't find circular pieces anywhere. A 1x1 is between the legs but supporting the "tabletop."

I then tied carpet samples around each leg and the 2x4 support toward the bottom so both vertical and horizontal scratchers are happy. It was VERY simple; Lowe's cut the wood to size before I could've even fired up my saw, and it's custom-fit to the window and the heater. CHEAP too!!