These measure 36" x 36" and each cube is approximately 12" x 12".
As you can see in the picture at top, I arranged them in to a rectangular shape by putting one on each end and then two in between those. Now I have a mass of cubbies that measures 60" x 36" x 36".
Since my table sits on a carpeted floor I needed to attach them to each other so that they would stay nice and tightly together. I did that by using mending brackets on the outside and L-brackets on the inside corners.
For the top cutting surface I intended to get a thin piece of wood to attach to the cubbies and lay a cardboard cutting board on top of that.
In the end I simply put the cutting board on top (I had to cut off one panel) and attached it with some double sided mounting tape. It has worked out great and has been plenty sturdy enough to cut on.