Top-Down Design

In top-down design, you do all the modeling within the assembly product. As you model items, you can reference the geometry of other items to create associativity between parts. You often start with a layout sketch, which you can also reference.

In this example, the layout sketch defines the overall layout of multiple components. Once the layout sketch is complete, you create solid bodies from the sketch profiles.

Create a layout sketch of your mechanism. Optionally use Instant Motion to test the mechanism.

Add components using the Insert New Component command from the Assembly section of the action bar. Extrude from the layout sketch or use the layout sketch as a guide to create new components.

Add additional features, components, and mates as necessary.

Alternatively, you can follow a simplified workflow:

Create a sketch mechanism by clicking Sketch Mechanism from the Sketch section of the action bar. Optionally use Instant Motion to test the mechanism.
Create 2D components by clicking Sketch to Components on the Assembly section of the action bar.

Extrude from the 2D components or use the sketches as a guide to create 3D parts. You can also open components in their own tabs to add features.