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Unit 03 · Lecture 4

Rectangular pattern, shared sketches and mirror

Constraining one shape per quadrant took a while. Filling each quadrant by hand would take all day. This lesson turns the sketch from the previous lecture into a grid of hundreds of shapes, extrudes it twice from one sketch, then mirrors the whole solid.

Video 14:10Reading 8 minUpdated 26 October 2026

Lecture video, 14:10. The written steps below follow the video, with timestamps for each part.

What you will build

The 500 × 500 mm base plate, 20 mm thick, with every patterned shape standing 50 mm above it, and a mirrored copy 100 mm above the top.

You will learn

  • Rectangular Pattern in a sketch: geometry, two directions, count and spacing
  • Editing a sketch pattern after you create it
  • Using Apply to extrude one sketch twice (a shared sketch)
  • Selecting all profiles and Ctrl-deselecting one
  • Offset work planes and the 3D Mirror feature

Before you start

Open your sketch from Geometric constraints (Part 2): the 500 × 500 square with four constrained shapes.

Step by step

  1. 01

    Pattern the small square

    0:45

    Open Rectangular Pattern. Select the four lines of the small square as Geometry. If you select something extra, Ctrl-click it to remove it.

    For Direction 1, pick a horizontal edge of the big square and flip the direction if the preview points outwards. Set the count to 16 and the spacing to 15 mm. The count includes the original.

  2. 02

    Add the second direction

    3:32

    Click Direction 2 and pick a vertical edge. Use 16 and 15 mm again. You get an even 16 × 16 grid that fills the quadrant.

  3. 03

    Pattern the other three shapes

    4:35

    Repeat for the circle and the hexagon. The triangle is larger, so use 10 copies at 24 mm in both directions. The status bar still reads Fully Constrained, because patterns inherit the original’s constraints.

  4. 04

    Edit a pattern later

    5:58

    Expand Sketch1 in the browser. Each rectangular pattern is listed there and can be reopened to change its directions, count or spacing. Older versions of Inventor didn’t allow this.

  5. 05

    Extrude the base, but click Apply, not OK

    6:39

    Press E, select the base region and extrude 20 mm downwards. If you click OK, the sketch is consumed by Extrusion1 and becomes hidden. Click Apply instead. The dialog stays open and the same sketch remains available for a second extrusion.

  6. 06

    Select 868 profiles in one move

    8:03

    For the second extrusion, select every profile with a window selection (Inventor reports 869). Then Ctrl-click the one region between the shapes to deselect it. That leaves only the patterned shapes. Extrude them 50 mm upwards and click OK.

  7. 07

    Create an offset work plane

    11:05

    Open Plane → Offset from Plane in the Work Features panel. Click the top face of any patterned shape and enter 100 mm. Work Plane1 appears in the browser.

  8. 08

    Mirror the features

    12:36

    Open Mirror (Pattern panel). Select Extrusion1 and Extrusion2 as Features, then Work Plane1 as the Mirror Plane. The copy lands as far beyond the plane as the original is below it.

Shared sketches

One sketch, two features

After the second extrusion, Sketch1 shows a small “shared” symbol in the browser. Both extrusions now depend on it. Change a dimension and both features update. That’s useful when they should always match, and a problem when you later want to change only one.

2D patterns vs. 3D patterns

A sketch pattern copies geometry along reference lines. A 3D pattern or mirror copies features about planes or axes. The order of selections is the same in both: what to copy first, then the reference.

Common mistakes

Practice exercise

Sketch a 200 × 200 mm square on the origin with a Ø8 circle 10 mm from one corner. Pattern it 10 × 10 at 18 mm. Extrude the plate 5 mm and the circles 15 mm from the same sketch, then mirror both features about an offset plane 30 mm above the top.

Check yourself

Does the pattern count include the original shape?

Yes. A count of 16 gives the original plus 15 copies.

How do you keep a sketch available after the first extrusion?

Click Apply instead of OK, so the sketch becomes shared.

What is the fastest way to select 868 of 869 profiles?

Select all, then Ctrl-click the one profile you don’t want.

The original is 100 mm below the mirror plane. Where does the copy appear?

100 mm above the plane.

Want the graded version? Take the 5-question lesson quiz in the course player after the video.

Written by the CADsmit instructor from the lecture recording and checked in Autodesk Inventor Professional 2027. Last updated 26 October 2026. Spotted an error? Tell us.