With the blocks all of the same shape and the edges sanded we can sand the faces. Instead of sanding all of the faces individually, we clamped a low frame around all of the pieces and sanded the entire group. Using the mobile workstand for this step was a pleasure. Using a low-grit sandpaper, we rounded the edges just a bit; extensive rounding over will destabilize the stack when you are all finished. You can also use a router to round the edges, but since we are just knocking off the corners, we did it by hand.

During this step, it is critical that you maintain the flatness of the faces. Remember that these blocks are intended for stacking, so the faces must be flat. Just like the sides, we completed all of the face sanding at this stage because it is much more efficient to group sand as opposed to sanding the blocks individually.

After you have completed all of the sanding, stack all of the blocks and make sure that all of the pieces sit flat on each other. If you can rock the stack slightly try to isolate where the problem is, and sand or plane it flat.