http://www.kickstarter.com/projects/ttstam/openbeam-an-open-source-miniature-construction-sys/widget/video.html

If you’re gearing up for a 3D printer, home brew CNC machine, camera rig, robotics, or automation project and are looking for a mini t-slot solution that uses common off-the-shelf fasteners, then check out OpenBeam. Redmond area maker Terence Tam based his t-slot design on the metric system, 3mm building blocks, and standard M3 nuts and bolts. All joining plates are molded metal-replacement engineering resin with a 3mm thickness to match the most commonly used materials on a laser cutter. It also includes an ingenious keyhole slot that runs down the center of the extrusion length that can be tapped for joint options or used to capture 3mm material and PCBs. [Thanks, Matt!]