That size and the ability to cut aluminum require a good bit of rigidity. If go look at my build here http://www.mycncuk.com/forums/router...d-machine.html and look at what the machine looks like, you see a machine that has a 845 x 345 x 135 cutting area (a bit more really but that is what I use). It is also rigid enough to cut metal. Though only weak spot in it currently is the spindle and a SuperPID or upgraded spindle would deal with that. If you know folks that weld near you, for the money you want to spend you could build or have built a machine that will do what you want.

Michael