A 3D model is printed from the CAD files to determine if the shape and dimensions look appropriate. Even though the model is visible in the CAD program, a physical model can appear slightly different than the design may appear on the computer screen.

The wire frame view lets allows the designer to see other walls or surfaces in relation to other features of the model (ie. the cavity and the face of the putter or the shaft hole and the bottom of the putter).

This shows the raw milling and 3D printed model side by side - they are the exact same dimensions although the picture makes the raw head look much smaller.