Bitbeam = Lego + Grid Beam = Awesome
The wood for Bitbeam is easily sourced at any major art supply store. (Ask for the craft/hobby woods section.) Basswood is recommended over balsa, as basswood is stronger. Next, head to your nearest laser cutter and start cutting your bitbeams.
Bitbeam height and width is 8mm. Each hole is 4.8 mm in diamater and 8mm apart from each other -- just like Lego Technic.
The advantage of building your own Bitbeam parts over Lego is that 1) the materials are cheaper, 2) I can make parts in sizes that Lego doesn't make, and 3) playing with lasers is fun!