Cutting foam is pretty tricky without a hot wire cutter ... He designed the frame in SketchUp and cut it out with his CNC router, although a saw will work just as well for MDF.

[Marius Hornberger] has been busy hacking his “Hammer” CNC router again, and now it sports a much desired feature — an automatic tool-changer. Having wanted one for a while, [Marius] was ...