Complex sentence: Surgeons use models to help plan surgeries but prosthetics and technologists also use then as an aid to the design and manufacture of custom-fitting implants and medical models are frequently used to help in the construction of Cranioplasty plates for example.
Split into simpler sentences: Surgeons use models to help plan surgeries but prosthetists and technologists also use models as an aid to the design and manufacture of custom-fitting implants. Medical models are frequently used to help in the construction of Cranioplasty plates for example.