Mini-T beams by Makerbeam

This is created from the specs Makerbeam posted on Scribd. It is 40 mm tall but you can modify the sketchup file to the 10cm (100mm) that Makerbeam beams will be avaiable in.

Makerbeam - http://makerbeam.com/whatsnext.html
Scribd post - http://www.kickstarter.com/projects/701662757/makerbeam-an-open-source-building-kit/posts/18107

UPDATE: Uploaded a 10cm beam in .stl format.