The size and the shape of the box determines the potential tower configuration. The cardboard box tower pictured below was a combination of two long, narrow boxes taped together on their vertical axes. It just so happened that the combination of the two was the exact width of the table so it could be taped down to the lip of the table to make it secure. Holes were cut in the sides and on hole was cut on top of only one of the boxes. There was also a window cut between the boxes. Access to that inside hole was more of a challenge because the children had to reach into one of the boxes to use it for their play.
A box tower does not need to be made from multiple boxes. The box tower below was made from one computer box. For this box tower, the holes on the sides were smaller, but the holes on the bottom were larger and opened out into the table.
Here is another box tower made from one box. That is not exactly correct because I did add a channel box horizontally through it.
The child found a sieve and placed it on top of the box over the hole. She added sand and shook the sieve back and forth. When she was done, she was pleased to display what her machine produced.
Here is a box tower made from six boxes, six liquor store boxes. In a way it reminds me of a pyramid with steps on two sides. However the steps all have holes. The holes are formed by cardboard packing panels taped onto the top of the boxes. Things dropped through the holes fall down to the bottom of the table.
On the left, the children inserted a loose cardboard tube and filled it. They were experimenting with volume. On the right, the child referenced his own actions in the box through the hole above. He was honing his proprioception.
Here is one last box tower. This was made from six boxes that were larger and of different sizes. There were actually two towers, one in each sensory table, that were connected by a horizontal element in the form of a box bridge.
The child on the left examined the space inside the small tower by bending under the bridge. The child on the right put sand into the bridge, a much different experience than dropping it down a tower.
There is really no limit to what a person can build in terms of box towers. But why build in the first place? I would be disingenuous if I said I did not get a certain amount of satisfaction to see what I can come up with. Everybody needs a creative outlet and this has been mine over the past 28 years. I do have another motive which is just as important: I am extremely curious about how children explore and investigated spaces, both large and small. By offering built spaces, I get a chance to satisfy that curiosity. Given the time to explore and make it their own, the children manifest their own curiosity in ordinary and extraordinary ways. In other words, my curiosity feeds their curiosity. Since their curiosity is boundless, their is no limit for the play possibilities in and around these built structures.