Various systems of extruded aluminum. Mostly t-slot.

<http://reprap.org/wiki/Extruded_Aluminum>

* [80/20](http://www.8020.net/t-slot-2.asp)
* [makerbeam](http://www.makerbeam.eu/)
* [openbeam](http://www.openbeamusa.com/)
* [makerslide](http://makerslide.com/), 20x40mm extruded aluminum with rails built in (for linear bearing systems)
* [gridbeam](http://gridbeam.biz/)