Before Campana starts designing, he studies his patient’s anatomy, the physical structure of its body. “For each species you have to know what you’re working with structurally,” he says.
Next, Campana makes a fiberglass cast of the part of the animal’s body where the device will attach. When Campana is building a brace, he may make a cast of an entire injured leg. If he’s building a prosthesis, he makes a cast of the stump that’s left of the limb. Once the hard cast is removed, Campana fills it with plaster, a thick liquid mixture that hardens as it dries.
Campana then uses soft plastic to shape the prosthesis or brace tightly around the plaster. He makes some pieces with a 3-D printer—a machine that creates objects by building them up in layers. Finally, Campana adds bolts, gears, and other pieces to allow the device to move like a real limb. He often adds a layer of textured material, called a tread, to the bottom of the device. That keeps the animals from sliding when they walk.