I was recently given foam and decided it would make a good ottoman. I wanted it to be approximately the same height as my couch so if I wanted to use it as a separate seat I could or as a table or as an extension to the couch.
Step 1: The Frame
I started with two 2x4x8 pieces. I wanted the ottoman to be 3x4'. I cut the 4' lengths first by halving the 2x4 then evening them with a second cut creating two pieces slightly shorter than 4'. I repeated the process to make the two 3' pieces. Then using the table saw I cut a 1/16" off of each of the sides to square the sides. Using a planer all 4 sides of each board were planed. I placed the 3' sections inside the 4' sections. Then using 3/8" dowels with one at each corner and nails I connected the pieces with butt joints. Finally I cut several left over pieces of wood with 45 degree angles at each end and attached the pieces with screws to brace it. I then used the left over scraps from the first 45 degree cuts to brace the corners and attached them with glue and nails. I also added another another ~4' 2x4 for additional support in the center once finished.
Step 2: Support for Foam
Using a burlap material I already had I cut a piece approximately 3x4'. I then cut strips of cardboard 1cm in width and as long as the braces. The cardboard was then wrapped with the burlap and stapled to the braces. I also drilled holes for legs in the support pieces and installed 7" tall legs I took off an old couch but many things would work as they are hidden.
Step 3: Almost Done
Using 5mm thick plywood I cut strips slightly wider than the width of the side 4" and top width 2" with the blade at 45 degrees a along the length of the strips. I then cut the side pieces to length again with the blade at 45 degrees on each end. Then addressing the top pieces I again cut the ends with the blade at 45 degrees and the ends cut at 45 degrees. The pieces were then glued and nailed to the frame. Everything was then filled/patched and sanded. After inserting the foam I decided to route the inside edge flush with the frame. I also routed the bottom flush leaving a slight overhang at the corners.
Step 4: Paint
Finally finish as desired, I went with paint. I still have to find the right material to cover the foam but so far my girlfriend and her rabbit love it. In retrospect I wish I had made it narower, finished with solid wood and rounded the edges. I am pretty sure I am going to cut myself on a corner and bleed out. Now to find the right animal print fabric and install the black lights underneath, wish me luck.