Lesson 3: 3D Design with 123D Design

Complete notes can be downloaded here.



3D Design involves thinking and creating in 3 dimensions.

x, y, z axis

X, Y and Z Axis      3D axes  


Working with 123D Design

123D Design is a 3D design software package from Autodesk. A free version is available from the following website.

Download the software: http://www.123ddesign.com/design
Video tutorials: http://www.123ddesign.com/howto/design


Pan – Hold the middle mouse button and drag. Moves your view of your current plane left, right, up or down

Orbit – Hold the right mouse button and drag. Allows you to adjust your view around your object or space

Zoom – Scroll the wheel. Magnifies your view

Fit – Select the object and press “F”. Fits the object(s) in your view.

The “view cube” allow you to directly move to the indicated plane of view. Useful to allow you to realign your view.

The View Cube

Creating Objects

Objects and parts can be created using two methods or a combination of the two:

  1. Drawing 2D Sketches and extruding / lofting to create the 3rd dimension
  2. Combining primitive 3D objects together


Drawing 2D Sketches, then Extruding / Lofting

Sketch 1    sketch 2

Extruding a 2D sketch will create a 3D object by giving it depth (or height).

Extruding a 2D sketch into an existing 3D object will subtract material from the 3D object. Extruding completely through the target object will create a hole.

Extrude in 1  Extrude in 2  Extrude in 3




Similar to extruding, except you can “extrude” up to the next sketch at a different level. Lofting from one level to another will produce straight edges. Lofting from one level to multiple levels will create curved edges.

Loft 1  Loft 2  Loft 3


Loft between different sketches

Loft example 2  Loft example 2 - done



A new object can be created by revolving a 2D profile or sketch around a reference axis.

Create several sketches that resemble the desired profile. Create an axis about which the profile will revolve, or choose an existing axis in your design.

Note that you may need to create “reference objects”. Reference objects or sketches are just visual aids that help you create your real object or sketch.



Creating Objects Using 3D Primitive Shapes

Create standard 3D primitive shapes and combining them together can create complex 3D parts.

  • Cube (length, width, height)
  • Sphere (radius)
  • Cylinder (radius, height)
  • Cone (radius, height)
  • Torus (major radius, minor radius) – looks like a donut or inner tube


Primitive shapes

Moving In 3D Space

You can move sketches or objects around in 3D space.

  • Mouse over the sketch or object until it turns green, then click to choose


Moving An Object

  • If an object is selected, a set of popup icons will appear.

Object icon menu short

  • Click on the first icon that looks like the 4 directional arrows (x, y, z and rotate)
  • Move the object along the x, y or z axes by sliding the directional arrows
  • Rotate the object by moving the circular icons

Move Rotate object


Moving A Sketch

  • If a sketch is selected, a gear icon will appear. Mouse over the gear icon to expand the icon menu option.

Sketch move


  • Click the first icon that looks like the 4 directional arrows (x, y, z and rotate)
  • Move the sketch along the x, y or z axes by sliding the directional arrows
  • Rotate the sketch by moving the circular icons

Sketch move rotate


Combining Objects

Once you have objects created, you can combine them in various methods to create different objects:

  • Merge
  • Subtract
  • Intersect


Merge An Object

Merging two objects will combine two objects into a single object.
Choose a “Target Solid”, and then choose a “Source Solid”. The order does not matter.



Subtract An Object

Subtracting an object from another object will remove the parts of the second object that overlaps the first object target.

The “Target Solid” is the object from which you want to remove material. The “Source Object” is the object that is doing the removing.

The new object will have material removed where the second object overlapped the first.

Subtract  Subtract result


Intersecting An Object

Intersecting an object from another object will keep the parts that are overlapping.

Choose a “Target Solid”, and then choose a “Source Solid”. The order does not matter.

The new object will be the intersection (or overlapping material) between the two objects.

Intersect   Intersect result


Choosing Multiple Objects or Sketches

It is sometimes necessary to choose multiple objects or sketches and perform actions on them: move, rotate, extrude, etc.

To choose multiple objects or sketches, mouse over the object or sketch until the outline it turns green, then left click to choose. Go to the next object and mouse over until the outline of the second object or sketch turns green. Hold down the CTRL key and left click.

Multi highlight

Cut or Slice An Object

It is often necessary to cut or slice an object. There are several methods this can be performed and no single method is considered correct.

  • Extrude or subtract
  • Slice by splitting


Slice by Extruding

Not the most exact method if you want two equal halves of an object.

  • Create a sketch larger than the object profile
  • Move the sketch to the desired location
  • Extrude the sketch by a very small amount so that some of the material of one half is removed. You can tell by the red extrusion

Slice by extrusion  Slice by extrusion result 1 Slice by extrusion result 2


Slice by Subtracting

Similar to the previous method, slice by extruding, but instead of slicing a small amount, extrude all the way through to remove the entire half.

Slice by subtraction


Slice by Splitting

Slice by splitting will require you to create a splitting entity. A splitting entity can be a is a line or the edge of an object or sketch. If you need to create the splitting entity, it is sometimes necessary to create a reference object on which to create the splitting entity.

  • Create a reference object
  • Create a line on the face of the reference object at the plane which you are splitting your object
  • You may delete (or hide) your reference object
  • Choose “Split Solid” in the Modify menu
  • Choose the “Body to Split”, and then choose “Splitting Entity”. The Body to Split is the object you wish to split and the splitting Entity is the line you created earlier
  • A red plane will be shown which shows you were the split will occur. The plane will split all objects that are currently shown in your view (hidden objects are not split)
  • Click anywhere on the background and the object is not perfectly split with no loss of material

Slice by splitting 00  Slice by splitting 01

Slice by splitting 02  Slice by splitting 03

Slice by splitting 04  Slice by splitting 05


Using Circular Pattern To Duplicate An Object Around An Axis

If you wish to create a repeating object around a circle or an axis, use “Circular Pattern” in the “Pattern” menu

  • Choose the object(s) you wish to duplicate as a pattern
  • Choose “Circular Pattern” in the “Pattern” menu
  • If you have more objects to choose, select the “Solid/s” and choose the objects
  • Select the “Axis” around which to duplicate the object

Circular pattern  Circular pattern 1


Split Multiple Objects Using “Split Solid” Along a Circular Plane

You can also split the circular patterns using along a circular plane similar to the Slice by Splitting method 

Slice by splitting (circle)  Slice by splitting (circle) 1

Slice by splitting (circle) 2  Slice by splitting (circle) 3

Slice by splitting (circle) 4


Chamfer and Fillet

Chamfer – Cut away an edge or corner to make a symmetrical sloping edge

Fillet – Create rounded edges

chamfer fillet