A T-Slot extruded aluminum framing system with a 15x15mm profile. Applications include machine building, prototyping and robotics applications and of course 3D printers.

Beams are sold individually, this beam is 60mm length with black anodising.

OpenBeam was designed to be a low cost construction system aimed at the hobby and Maker market.  OpenBeam is based around the metric system and 3mm building blocks. To keep the cost of the system low, it uses standard M3 nuts and bolts, available at any good hardware store as well as ourselves of course.  No special fasteners are required. 

OpenBeam connector plates in both 'L' & 'T' formats are injection molded out of a metal-replacement engineering resin. The beams come in various lengths from 3 to 1000mm long. They may be user cut with a hacksaw, mitre saw etc.

The most commonly used materials on laser cutters in the US are 3mm baltic birch and 3mm acrylic.  All joining plates are therefore designed to match this thickness to encourage users to cut their own custom plates for special applications.  The T-slot can be used to capture a 3mm thick panel; 5 sheets of material may be stacked together to match the width of the extrusion, which measures 15mm x 15mm.

There is a hole down the center of the extrusion length that can be tapped for a M3 screw to allow the extrusions to terminate in a butt joint against another member.  The small groves in the center of the T-Slot serves two purposes; to guide a drill in drilling through the extrusion, and to capture a standard thin gauge circuit board.  Thick gauge circuit boards can be captured via the keyhole slot.