This fun little puzzle cube project is the second assignment of my 8th grade "digital manufacturing" elective class when we start exploring Fusion 360 and 3D printing.

Our elective explores Computer Aided Design and the design process in general. This is a new course for us (2nd time through), so we are slowly adding lessons and tools (for example, adding a laser cutter this year, and working with a nearby high school to perhaps try out some CAM and CNC).

For learning targets, this lesson is used mostly to get some more hands-on understanding on the fusion program (developing more comfort), but we also use it to talk about tolerances and units (a bit of math), and we use it to talk about drafting and 2D to 3D drawing. Finally we use it to re-introduce some of the design/engineering concepts from 7th grade such as iteration.

Some examples of learning targets used in this project:

I can relate three-dimensional models to two-dimensional representations, and vice versa.
I can utilize the PATTERN tool to quickly duplicate 3D bodies in an organized manner
I can correctly DIMENSION a sketch in order to create a puzzle cube with the correct proportions.
I can use the RENDERING tools to create a photorealistic image of a 3D model.

As a beginner project, this uses mostly basic moves in the program (Sketch, Dimension, Extrude, and Rectangular Pattern) but the result is impressive from the view of the kids and others who see the end product.

Supplies

Computer Aided Design Program (here we used Autodesk Fusion 360)
3D printer and fillament

Step 1: Make a Single Unit Cube

Use the CREATE SKETCH tool and click on the "floor" plane (for my students this is the XY plane)
Using CENTER-POINT-RECTANGLE draw a rectangle
DIMENSION the rectangle to have sides of 25 mm each
Then STOP SKETCH
Back in the model workspace, EXTRUDE the square 25 mm, to make a cube

Step 2: Pattern the Unit Cube to Make a BIG CUBE Out of Little Cubes...

You will use CREATE: PATTERN: RECTANGULAR PATTERN to turn your one little cube into a cube of many. The number that you choose to pattern with will determine the complexity of your puzzle cube. In this example, I have patterned out a 4x4x4 cube. You could do this with a 3x3x3, or with anything larger.

In the CREATE menu, click RECTANGULAR PATTERN
Set up the Pattern Menu as follows:
- Pattern Type is BODIES
- Object - click to select the cube that you made in step 1
- Directions- click on on edge of the cube
- Distance Type- Spacing
- Quantity- 4 (or your choice of cube number)
- Distance- 25.6 mm
- Quantity-4
- Distance- 25.6 mm
This will have created one layer of cubes in a 4x4 pattern.
Repeat these steps, selecting ALL of the cubes to pattern them upwards to complete your cube.
At this point, it should look like the third image shown here.

Step 3: Extrude to Combine Cubes Into Unique Shapes

Now we begin to form our unique puzzle pieces. This is where you can get creative. Two guidelines to follow- try not to leave any single cubes behind, and try not to repeat shapes.

Select the EXTRUDE tool (from the create menu, of "E" on keyboard)
Click on one or more inner faces of your little cubes
Extrude those faces just enough to JOIN them to the cubes next door, creating new shapes. (See the two examples).
Repeat ( Repeat a lot)
It helps to use the light-bulb/eye in the browser menu to hide puzzle pieces that you are done with so that you can access inner cubes
When you get toward the end you might find leftover cubes. Oops! Un-hide some of your other shapes and extrude to join those too.
Play around until you like your shapes. In the end you will have something like the 4th picture here.

Step 4: Change Appearances

Use MODIFY- APPEARANCE to drag different colors onto each segment of your puzzle cube.

This will make it easier to see if you like all of the shapes, and will make it easier to identify pieces in the other steps of our project.

Step 5: Round the Edges

Use MODIFY-FILLET to round all OUTSIDE edges. Do not round the inside corners. The easiest way to do this is as follows.

In the SELECT menu- change SELECTION PRIORITY to SELECT EDGE PRIORITY
HIDE all but one piece.
Open the FILLET tool
BOX select the entire piece.
CLICK to UNSELECT any inside corners
FILLET all the other selected corners at 2.00 mm
REPEAT everything for all puzzle pieces

Step 6: Admire Your Cube- Now Customize!

At this point you are done! You made a puzzle cube. Each piece can be saved as an .STL and printed on the 3D printer.

But what ELSE can you do?

Try to make a container for your puzzle cube- you can do this with the tools you have learned so far! It is really just box, but you can make it look awesome!
Draw on the sides of the cube! Sketch something and extrude it into the sides- Maybe a secret message that can only be seen when assembled correctly....

Step 7: What Next?

My students also use this as the first design that they RENDER in Fusion 360 and the first design that they test out the DRAWING workspace with. We also try out the ANIMATION workspace and send the puzzle cubes into an exploded view.

Obviously these are not things that you will do if you just want to make a cool 3D printed puzzle cube, but if you are using it as a learning/teaching tool for CAD- it works well for introducing those two workspaces.