I haven't begun my mill retro just yet, but I have posted a pic of my lathe Camsoft retro. This was a small manual Graziano lathe originally with a Bandit1 controller. This brand of lathe has an 8-speed electric shift gearbox for driving the spindle, which is really a nice feature for a cnc lathe. I can always run the machine in the optimum torque range without having to go to a 20 hp motor
Anyways, you can see the cabinet I used. This was the existing controller cabinet, I simply hacked out a hole and mounted a 17" monitor inside. I used the original set of manual buttons, shown in a row below the monitor. I mounted the keyboard above the monitor, which is not handy for extended typing, but is fine for running the machine. I purchased a keyboard with a built in touchpad, which I find quite convenient for mousing about with simply a fingertip. You can see the little touchpad as the dark rectangle in the keyboard.
I mounted a glass cover in a boxed in area over the keyboard, about 6 inches above it. This keeps random chips from flying into the keyboard. Access to the keyboard is from the bottom side. Fortunately, my arms also approach from the same direction
I am thinking of something a bit fancier for the mill. I was dreaming of a clear acrylic "hutch", suspended from a swinging pendant arm. Using extended cables, I would mount an LCD monitor, keyboard and mouse on this arm, and leave my computer in a large cabinet affixed to the machine, some distance away and out of the road. This other large cabinet would contain the servo amps, Galil interconnect module, etc.
I have also purchased one of Camsoft's neat little "operator pendants", which will contain the most oft used I/O functions needed for running the machine. This will eliminate the need for me to make a new operator panel of my own. The machine currently has a Shadow controller on it, and when I remove that, all the existing operator panel goes with it.