I spent many years running a welding shop building various oilfield equipment before i dabbled into drafting and design. Autodesk Inventor was the program of choice as it runs well, easy to use and works really well for the tasks involved. It's only downfall is that it runs mainly off one cpu core, unlike others that utilize multi-core processing. I have always played a vital role in the design of this equipment.
Modeling was an instant addiction.
All these pictures have been taken by myself of rigs I designed/built over the years.
Read next