In this Instructable you'll learn to take any 3D object and "slice" it into 2 dimensional sections using Autodesk's 123D Make app. Then we'll take those sections and laser cut them out!

Note: Autodesk has a great instruction manual for using 123D Make. Find it in the Instructables folder on the desktop.

Step 1: Select an Object

Open up 123D Make from the computer's Taskbar. The icon is an upside down green and teal icon. Once the program is open, open up an example file or import your 3D model. Don't like the examples and don't have a model of your own? Go to Thingiverse.com and download something cool!

Step 2: Setup Your Manufacturing Settings

Now we need to tell the program the size of the material that we'll be using. Click the pencil icon under Manufacturing Settings, then click the + button in the bottom left of the popup. Give your new material a name, and specify its size. Note: the thickness is VERY important to get correct. The more accurate the better otherwise your pieces will be difficult if not impossible to slot together or they may be so loose that your object falls apart. Its best to know the exact size of your material as stated by stickers or a label on the material. But if you can't get that, then use calipers. Don't just estimate with a ruler - it won't be good enough.

An important setting is Slot Offset: Set the cut width to determine how wide the actual cuts on your cut sheet are. The cut width is based on how much material your cutting tool (laser, saw, etc.) removes. This makes assembly easier. A slot offset of "0" creates a notch that equals the material thickness. Depending on the material you intend to use, a Slot Offset of 0 could make assembly difficult to slide one piece through another. Decreasing the slot size will force slices to have to squeeze together (fine for cardboard), increasing it allows for "breathing room" in the notches during assembly (helpful if your material, for example plywood varies slightly in thickness).

When I did this example, my pieces were a bit tight and hard to get together. If I were doing it again with the 5.2mm thick plywood veneer, I would add a 0.02 slot offset or so.

Step 3: Choose Your Construction Technique

123D Make offers a handful of construction techniques that can be used for varying effects, strength, aesthetics, and material efficiency. Select a few different ones to get an idea for what each one offers. In this Instructable I'm using the Interlocked Slices technique. If you choose a different technique, the following steps will still apply to you.

Once you settle on a technique, you'll have several options available to you. The most important one for interlocked slices is the number of slices in each axis. Play around with the numbers until you find what you want.

Notice that the right panel shows your material and all of the slices the program is generating. Sometimes some of your slices will turn red. This means there are errors with those slices and you need to ensure they will be okay or go back and change your settings to eliminate errors. You can also manually position slices to make sure you capture certain features of your model, or to eliminate errors. There are also features to modify (thicken or reshape) your 3D model to get better results. Play around!

Step 4: Export Your 2D Parts File

Once you're happy with your slices, its time to export to a DXF. In the bottom left of the left panel, select 'Get Plans'. Set your layout to 'Nested' to save material, and then in the bottom center of the screen select for DXF in mm output, and then hit Export.

Step 5: Prepare Your File for the Laser

Open up RDWorks (the red icon in the task bar)
Import your DXF file
Position all of your pieces in the upper right corner of the workspace.
Edit the red layer so that it will not be output to the laser
Edit the blue layer to have a power of 85 and an appropriate speed. You'll want to have run our test file on your material in order to determine your optimal speed setting!
Preview the job, and if all looks good, download it to the laser machine.

Step 6: Laser!

Position your material
Set your Z
Set your origin
Select your file
Frame
Fire!

Step 7: Assemble

See that piece of material that looks like trash because it has a bunch of piece holes in it? Save it! When you pull out your pieces, you want to use this as a template for getting them back into their original layout so that the computer can help you with assembly.

Get all your pieces laid out on the table in front of the computer in their original layout. Go back to 123D Make and select Assembly Instructions on the left panel (near the bottom). Click through the timeline (at the bottom of the screen) and assemble your model. Notice how the piece your on becomes highlighted in the right panel.

If your pieces are hard to fit together or too loose, you're kind of out of luck. You might try a mallet, snadpaper, or glue, but good luck. For best results you'll need to go back and change your Slot Offset in your Manufacturing Settings and cut out your pieces again.

Congrats, you're finished!