Anyone! Any body type. Any age over 18 years old. If everyone looked the same, artists would have become really bored drawing models by now. All that is required is a desire to become a model, punctuality, and a good attitude. Many groups are willing to work with inexperienced models that show promise.
While there are people who work exclusively as artists’ models, most people become models to supplement their income. Many are artists, actors, or dancers. Others are fitness instructors, teachers, students, salesmen, or store managers. In other words, anyone from any walk of life can become a model!
As a rule, a model has to be physically capable of holding a pose. That can mean being able to hold still for up to 30 minutes without moving for some classes.