Jonathan Ward from the MIT Center for Bits and Atoms has designed a snap-together, desktop-sized CNC milling machine. The MTM Snap (part of the Machines that Make project) is made from 1/2-inch high-density polyethylene (HDPE) – itself milled on a ShopBot – and can be assembled for about $700. This three-axis CNC machine can mill circuit boards, wax molds, and harder materials in a 5x3x1.75″ working area.

The MTM Snap is controlled by an Arduino board running grbl, a full-featured and robust g-code interpreter. A custom shield (designed by Nadya Peek) with three Allegro A3982 chips drives the machine’s stepper motors, and the whole thing is controlled from a simple GUI written in Processing. The advantage of this setup is that you can use the machine from pretty much any computer: desktop or laptop, Mac, Windows, or Linux. We use the CBA’s Kokompe tools for generating g-code files, but grbl should handle most files from other sources (like PCB-GCode).

You can’t yet buy the MTM Snap, but the machine has been designed to be as easy as possible to assemble yourself. All the design files are online if you want to cut out your own pieces on the ShopBot. The complete bill of materials is available, as are the documentation for the Arduino shield and software instructions.

If you’d like to see the MTM Snap in person, drop by the ShopBot booth at the Bay Area Maker Faire this weekend. It will be running off of an OLPC laptop.