World in Motion 🕹️ on Instagram: "Waddles the duck was born with a malformed left foot, which made it difficult for her to walk like other ducks. Her owner, musician Ben Weinman, contacted Derrick Campana from Bionic Pets, who designed a bright orange prosthetic using 3D printing technology. In the beginning, Waddles carefully adjusts to the new weight, but soon she takes her first steady steps. They are not perfect yet, but they clearly show her growing confidence and determination."

What are the three categories of engineering models?