Lines add fine detail to a 3D model and enhance edges... but not all 3D graphics systems are capable of drawing lines.
Lines enhance edges
Not all 3D graphics systems are capable of drawing lines. For example, the original PlayStation console could only draw triangles or triangle pairs ("Quads"). It could not draw lines or triangle strips so lines had to be simulated by drawing very skinny Quads instead.
3D Kit Builder
To show only lines in our example 3D Kit Builder model use the following Display options which are available when you finish building your 3D model kit: