A hole is cut in two of the panels on one side. The cardboard tube is threaded through the holes and taped. A section of the tube in the middle has been cut away. Now besides the open spaces created by the vertical walls of the divider, the tube creates both horizontal and closed dimensions to the apparatus.
In another version of this combined apparatus, an additional plastic florescent light cover is embedded in the divider. This configuration is a little different because the table is used to support one end of the tube and channel and both the tube and channel extend over the end of the table so children can push the sand out of the tube and channel into the tub below.