I just wanted to share some images of our 12x12 build.
Build time was ~5hrs, it was frustrating with only images and no text, but I worked through it. Also the wiki is very scattered, I found good information in the 7x7 build wiki that should really be in the 12x12 too. Some of the setups for Mach 3 are dated. The steps per minute was still listed for the older threads, not the f8's which led to some confusion. And the limit switch wiring was backwards. But never the less I got it working.
The wiring was roughed in quickly just to get it up and running, but yesterday I built an enclosure behind the machine to house all of the electronics.
Actual travel is ~13.5x13x6 right now. I could probably squeak a bit more out of it my removing the arms off of the limit switches.
I found the bed to be almost 2mm off corner to corner, so I used a MDF sheet, CNC'd it level to the machine and I'm good to go. It's smaller than the overall surface so that I still have access to the slots in the bed for clamping.
I found the Zen spindle easily slipped out of it's holder. I've added a few layers of tape for now and haven't had any movement, however a longer term fix may be needed.
Have a look!