With an emphasis on safety and performance, dozens of designs were made and tested using 3D printing technology and polyurethane casts. The final innovative design is composed entirely of natural rubber, eliminating the potential choking hazards found in many whistling products and producing a pleasant tone that successfully engages a dog’s keen sense of hearing. Chuckit’s patented variable welt design is incorporated for brand recognition, while a teardrop shape highlights the Whistler’s functionality.