Hi,
I build my own CNC Router for modell building.
You can see pictues and videos on [link=http://www.tron-cnc.de]http://www.tron-cnc.de[/link] (switch to english on the top right).
The router is quite cheap to build and is perfect for plywood and balsa and CFK.
You can buy a cheap plan as well (see onlineshop on the page).
Jens