I first produce a master blueprint connecting 2d sketches & reference planes in XYZ. All fabricated parts are derived from this blue print so any alteration to the blue print cascades through the design.

• Parts
• Assemblies
• drawings

3D assemblies are made by joining parts together with rules that replicate the physical world such as parallel, offset, rotate, absolute & rotate about, touch another point etc 

The parts can be given mass & material or visual attributes such as glass or steel 

We now have a 3D model that we can check for clashes & interference issues.

Any problems can corrected before any machining or fabrication is started.

Now the 3D model is complete 2d fabrication drawings & dxf files can be produced. Many different variations of the same assembly can be saved with different names.