Originally posted to the Ponoko Blog.
Update 2019: Autodesk killed the 123D apps :(
123D still exists in the form of the Slicer app. It's unclear if the standalone app is still receiving updates from Autodesk but it is also available as a plugin for Fusion 360 which I assume is getting regular updates. It also seems there is a bug with some of the template sizes so the cutting profiles may need to be re-nested in another design software to maximize material usage.
Update 2016: Since writing this post much easier way to achieve this process has come along with 123D Make. They even have Ponoko template size pages that you can layout your parts on for a seamless 123D Make to Ponoko workflow.
Every day I see a lot of good content go through my feeds and occasionally they are some real gems which lower the barrier for people to create great designs. I saw two SketchUp plugins a while ago and have only just had a chance to test them out. I am amazed how easy it makes creating sliceform laser cut models and I'm wondering how I ever did this before. I wish I'd known about these when doing this project with my students back in 2009.
The plugins are: Slicemodeler by Public Art International (available for a $10-$50 donation) and SVG Outline plugin by Flights of Ideas Slicemodeler allows you to take a 3D form and slice it up into interlocking pieces. It is so easy to use it is unbelievable! You enter the distance apart that you want the sections, the material thickness, choose which axes the slices are on, and the software calculates the intersections.
Once you have all the slices, that's when the SVG outline plugin comes in. Select the sections you want (that have been conveniently laid out by Slicemodeler) and hit Export to SVG file.
Now you have a file (or files) you can open in Inkscape or Illustrator to arrange for laser cutting. The SVG export plugin claims to be able to label your profiles but I could not get it to work with the labels that Slicemodeler adds to the parts. I manually added labels to the parts in Illustrator and then laid the profiles out on a P3 template.
And the finished article made from 1/4" cardboard.