Architecture firms usually employ model makers or contract model making firms to make models of projects to sell their designs to builders and investors. These models are traditionally hand-made, but advances in technology have turned the industry into a very high tech process than can involve Class IV laser cutters, five-axis CNC machines as well as rapid prototyping or 3D printing. Typical scales are 1:12, 1:24, 1:48, 1:50, 1:100, 1:200, 1:500, etc.