Durda's office is in a pretty chic district of Boulder — the spa next door might object to a couple huge cranes parked outside for a week — so he took the experiment to the Southwest Research Institute's main office in San Antonio, Texas. The two cranes he rented also came with operators Alan Rawlings (a.k.a. A-Ray) and Chris Vest, who are listed as co-authors (along with scientists Naor Movshovitz, Derek C. Richardson, Erik Asphaug and Alex Morgan) on Durda's paper. Durda said he was impressed with their interest in his unusual experiment, and was indebted to them for their suggestions about how to secure the spheres and release them for proper clacking. A-Ray came up with the idea to use zip ties to secure the balls at a set distance, for instance, and snip them with wire cutters to release the tension.