The intention is that you can model your idea in 3D and then produce it directly via 3D printing or CNC machining.

Figure 1: Autodesk 123D could almost be called “Fusion Light.”

To aid in this process it contains direct links to several rapid-manufacturing service bureaus including Ponoko, Shapeways and TechShop along with direct support for 3D Systems. Can you say “matter replicator?”

The genealogy of 123D is obviously heavily biased towards the Fusion side of the family tree, and in fact when I installed it my first reaction was that I had accidentally launched Fusion instead of 123D. 

The first thing that jumps out at you is the simplicity of the interface. No ribbon! No Command: line! There are only three interface objects:

1. The main toolbar
2. The navigation toolbar
3. A small collection of action buttons in the lower right corner of the screen.

Let’s start with the main toolbar. It is a “marking menu” interface, similar to that found in Fusion 2012 and Inventor 2012. Click and hold on a button and a set of command functions appears, arrayed around the button. Now move the cursor towards the desired function and release the mouse button to invoke the command.

The navigation toolbar will be very familiar to anyone who uses Inventor or AutoCAD’s 3D orbiting functionality to change your viewing angle of the model.

The button collection controls things such as snap on/off, grid on/off, and so on.Construction of a solid model is accomplished either by placing common shapes such as cubes, wedges, cylinders, disdyakis dodecahedrons, and so on from a library, or by drawing a 2D sketch. 

Figure 2: Would you believe that this started out as a cube with a hole in it?

Like Inventor and recent releases of AutoCAD the elements of a sketch can be controlled through geometric constraints such as parallel, perpendicular, concentric, and so on. Lengths and diameters/radii can be dragged to size, snapped to existing geometry, or specific values can be entered. Values can also be determined by entering a formula, but unlike Inventor or the parametrics in AutoCAD a formula cannot contain a reference to another size somewhere else.

Geometric constraints are automatically and manually added and dimension values are specified as you sketch. The flip side to history-free modeling is that once a sketch has been consumed into a solid then all relationships between the sketch and the solid feature are lost. 

If you forgot to add a geometric constraint then you are almost out of luck. I say “almost”, because the sketch still exists. You can always delete the feature, edit the sketch, and then create a new feature from the edited sketch.

Once a sketch is complete it can be extruded, revolved, swept, lofted, and so on into a solid.The process is then repeated as other features are added to, cut from, or intersected with the existing solid.Separate solids can also be created and then assembled using geometric assembly constraints.
Many of the normal editing commands you might expect to use don’t seem to exist. Actually they do, but you invoke them simply by clicking on a desired face or edge to bring up the appropriate context menu.

123D is a history-free, direct-edit modeler. This means that individual faces and edges can be directly edited and modified without regard for the sequence in which the solid features were created. They can be moved, rotated, and even free-form pulled and pushed into smoothly-flowing shapes.

Dimensions, called “Design Intent”, can be added to individual faces, edges, and vertices on the solid. If you change a dimension value then the model updates while still obeying the original geometric constraints.

123D has very limited 2D support. You can generate orthographic and isometric views but you can’t apply dimensions or annotations, and dimensions don’t carry forward from the 3D model. Remember, this product is intended to be a direct interface between the designer and the physical part.

It uses a proprietary file format, which is interesting because Autodesk have stated their avowed intention of eventually having just one standard file format for almost all of their products. You can “save as” in AutoCAD’s .DWG format or in the common neutral formats STEP, IGES, STL, SAT, and VRML. In any case, all that comes across is a “dumb” 3D model.

There are several significant points with regards to Autodesk’s 123D software. 

First, it is still a beta version and so may contain a few minor hiccups.

Next, it’s a fascinating 3D modeling program. No, it won’t replace Inventor or Fusion or even AutoCAD, but it is nonetheless a very powerful program. It is so powerful, in fact, that you shouldn’t be mislead into thinking that it is a “quick and dirty” app for occasional or amateur users. 

This is not “Etch-A-Sketch” software; as indicated earlier, it is more of an interface between designers and rapid prototyping/rapid manufacturing processes. I have a reasonably good laptop (Dell Precision, core 2 processor @ 2.5 GHz, 4 GB RAM, XP x64, nVidia Quadro FX 360M graphics) but it is being pushed pretty hard.

Finally, the really good news is that the beta version is available for free at http://www.123dapp.com/. 

So how do they intend to make any money from a free program? Answer: the MBA’s would say “They’ll make it up in volume.”