If you were going to build a Really Nice quality CNC Router with a cutting area of 4' x 4" that would not only cut wood and softer materials but cut brass, bronze and aluminum how would you build it with a budget in mind and if you have built something like this, please discuss what your build consisted of...
Items of concern we would like to hear and know...
A- What materials will it cut or is it strictly for wood and softer materials?
B- Construction materials...All aspects from the frame to the "Z" axis including the "Z: axis...Did you go as far as designing features in the "Z" carriage which incorporated addition machining to reduce the distance from the face of the gantry to the center of the spindle?
C- Design
D- What size of rails were used and what size ball screws were used along with the pitch you used on each axis...providing ball screws were used if not did you go gears and if so why?
E- Are you happy with it and if not, what would you change?
F- What size of NEMA motors you go with and why...Did you direct drive them or go with like a 3-1 ratio and if so, why?
G- Foundation the unit sits on which would be supporting from the floor to the unit?
H- Now for those that has built there unit is there any changes you would make now that you have used it for a while?

And if you have pictures to show off, please post your pride machines...Or if you did a video and has it posted on the net, please share link...
Perhaps a topic like this for prosperity would be a nice fit for future members who are avid about wanting a CNC Router but don't know where to start in designing with the right parts and items of concern that you guys have learned from and are willing to share...There is sooo much info out there to diverge thru it can be over whelming for a newb
Thanks
Paul