3D Printer/CNC milling Reference material

Hi, I would like to make a 3D printer because the hobby ones you can buy have a very small work area. I'm looking to build one that has an 18 cubic inch work area. I would also like to be able to flip the head 180 degrees like a CNC mill toolchanger and be able to interchange between an Extruder and a spindle that can hold up to a 1/4 inch cutter. I figure even if the part warps a bit, you can always clean it up with the milling head. I'd be machining the plastic parts and perhaps a PCB or 2. What I am after is some reference material please. My google/bing searches have been a little disappointing on finding good reasearch material and vendors.

Thanks,
Jes

3D printing is a hot topic and there are various open-source and cheap commercial options out there. I'm surprised that you haven't managed to identify any of them.