The art of the Technical Illustrator was basically to render a 2D object in a implied 3D look. To further give the illusion of depth, you'd draw all circles as ellipses. The most common angles for this type of drawing are 30/30, 10/45 and 20/45 degrees, or Isometric, Diametric and Trimetric.
I will foremost and always be a Technical Illustrator at heart, that's the one art form that I still enjoy more to this day. Give me a stack of top assembly drawings and get out of my way, now that's fun.
An isometric drawing could be anything from complex gear box or transmissions to a solid rendered object that fully displays details that would otherwise not be visible in a orthagraphic view.
These images are just a seletion of the many illustrations I have done.
1 is a transmission box off of an RMK-19 Tow Reeling machine and was done in pen and ink.
2,3 and 4 are solid renderings of neurological instrument head holders that I did for the David Kopf Instruments Company.
5 and 6 are Space Shuttle thruster junction box and injector face plate assemblies.
7 is a ramjet concept drawing.
8 is an isometric wiring diagram of an orbital automatic weld head.