Made a Canon Lens Model, exercise: to build a basic model included combining different materials, like glass, metal, rubber (with semi reflections) and some transparent plastic. The lens body is a very simple model with just a few extrusions from a circle with 32 verts.
All text and numbers printed on the lens is created from UV Unwrapping. Reflections made from an image texture with mapping set to Reflections. Rendered in Blender Render, and then with Anti-Aliasing set to 8 and Full Sample. Rendered with Subsurf Subdivisions set to 3. The scene contains one Point Light (tint of blue), one Point Light (tint of orange), one Area Light (tint of orange) and one Sun Lamp.
As mention, a basic model based on a few circle extrusions. The challenge (took a few hours) was to tweak the colors, materials and reflections to make it as real as possible. Well, hope u like it :-)