#Part: an overview

The Part workbench turns sketches into a body and refines that body further. The work goes through a history timeline: every command adds a node to it, and the whole order stays alive — go back to any step, change a number, and everything below rebuilds.

#A part is ONE body

The first material feature creates a body, each next one carries it further: an extrusion adds material, a cut removes it, a fillet reshapes it. Intermediate states do not pile up as separate bodies — you always see the result of the chain.

#Two kinds of commands

• From a sketch: extrude, revolve, sweep, loft. They need an outline.
• On the body: fillet, chamfer, shell, hole, draft, thread, arrays, mirror. They need edges, faces or the body itself.

Plus primitives — box, cylinder, sphere, cone, torus, prism: a body without a sketch, from sizes alone.

#The command contract

The same for all of them: pick what it stands on (an outline, edges, a face), set the values in the top bar or right at the geometry, watch the preview: Enter applies, Esc cancels. Until Enter the document is unchanged.

Every numeric field takes a formula: 40/2, len*2. Names come from the global parameters.

#Editing what is built

A double click on a feature in the tree reopens the same command with the same fields. Change and apply — it rebuilds, and so does everything that depends on it.