OpenSCAD code included for modifications. Just print on your favorite open source 3D printer and clean up. You will probably want to flip the stl and print from the easy side.
You'll need an m3 screw and nut along with the magnet. Put the screw through the base and screw onto the OpenBeam with an m3 nut. Then press fit the magnet on top of it. We have all these old steel desks that work as great bases.
If you do not have a metal base to put your open-source optical rail on you can just as easily make and openbeam into an optical rail by screwing on two T-brackets http://www.thingiverse.com/thing:30524
Next you will want to add some mounts -- see:
Simple 8mm rod holder: http://www.thingiverse.com/thing:31370
Complex side mount: http://www.thingiverse.com/thing:3049
You can get Open Beam at http://www.openbeamusa.com/Extrusions/
To get the magnets see http://www.rare-earth-magnets.com/
This project was developed by the Michigan Tech Open Sustainability Technology research group http://www.mse.mtu.edu/MOST
This component is part of the Open-source Optics Library: Zhang C, Anzalone NC, Faria RP, Pearce JM (2013) Open-Source 3D-Printable Optics Equipment. PLoS ONE 8(3): e59840.
This is part of a larger project to reduce the cost of scientific equipment using open-source hardware. Read more here
Thanks to Terence Tam for OpenBeam. Brilliant work!