Does a wider dome hold less weight than a narrow one? Because full domes are difficult to build, you test this with plywood arches that share the same structural properties. You bend plywood strips of increasing length into arches that all stand 100 mm tall. As the arch gets wider, the span (representing dome diameter) increases. You hang a pail from the center of each arch and add sand in 100-gram increments until it collapses. The wider arches fail under less weight. This shows that increasing a dome's diameter without raising its height weakens the structure.