Find your way around CAD

A solid model describes a bounded volume; a mesh describes its surface with vertices, edges and polygons. A watertight manifold mesh has no open boundary, and each edge belongs to two faces. Closedness alone does not rule out self-intersections. STL contains triangles, not the original sketch dimensions or feature history. Save the native CAD document and export a mesh for slicing. STEP commonly exchanges CAD solids; 3MF can carry units and more print data.

Set millimetres → choose a plane → sketch and dimension → build a feature → inspect → save the editable file → export for printing. Fusion and Onshape use a feature timeline/tree; FreeCAD calls extrude Pad and cut Pocket; Tinkercad often starts with primitives and Hole + Group. These are related ways of adding and removing volume, not identical interfaces. Check each application’s navigation preferences.

CAD

Software for creating and editing geometric designs.

Origin & axes

The zero point and X/Y/Z reference directions. Axis conventions can differ between applications.

Parametric model

Dimensions and relationships drive the shape, so editing a value can rebuild dependent features.

Manifold mesh

A surface with a consistent neighbourhood around each point. A printable closed manifold also has no boundary.

Find the view cube, Fit view, units, selection filters and model tree. Practise orbit, pan and zoom on a sample file before editing. A camera view is not an object transform: Move/Rotate changes the part itself.