World Trade Center Memorial mock-up helps designers plan for the future.

The article reports that the World Trade Center Memorial, called "Reflecting Absence," which will consist of waterfalls flowing into representations of the voids left by the Twin Towers, won't be finished for years. But a mock-up corner section of one of its voids has been built in the backyard of Toronto resident Dan Euser, a consultant to the project in New York. The $175,000 model, 27 feet high, is made of 300 plywood sheets and powered by three 10-horse-power pumps that send water over a serrated ledge. Since January 2005, Euser has used the model to examine issues like splashing, noise levels, self-cleaning, the effects of wind, and freezing.