My technical illustration uses a couple of different styles based upon what you need: Hard edge (click to see) and Bit Map.
The Hard edge style is customary for instruction manuals, product how-to's and fade away illustrations that demand a clear, stylized look.
The Bit Map method is traditional and perfect for realism. However, it does not scale up like Hard Edge and also produces much larger files.
Additionally, I can match existing photos and then do a reveal or cut away into the objects in the photo to reveal the technical aspects of the objects shown. This can also be done on live footage for trade show videos if required.