CAD & Drafting

The CAD category here holds four quite different kinds of tool, and it is worth not confusing them.

• 2D drafting — layers, blocks, dimensions and DXF files. For work that is mostly plans and details.
• 3D parametric modelling — a history tree that lets you go back and change a dimension without rebuilding. This is what mechanical parts and assemblies need.
• Code-based modelling — you write the solid as a program, and every dimension is a genuine parameter. Powerful when you need a family of parts rather than one part.
• Electronics design — schematic and PCB layout, which is CAD of an entirely different kind.

The common trap is DWG. Most free tools work well with DXF and open formats, but full support for current DWG is usually reserved for paid versions. If you exchange files regularly with an office running AutoCAD, check this before you commit.