electrical interference

I'm in the process of rebuilding a mill. I've got gecko 320's with
one of Bob's breakout boards. Nice, clean and easy. Now, to make it
even cleaner, I'd like to put the powersupply in the same box as the
new controller, but underneath (so, 60 thou of Al between them). Will
this create too much electrical interference, or should it be OK
below? Do I need to totally seperate the power supply and controller?

Also, is it OK to send the servo power and the encoder signals all
through the same conduit?

Now I'm on a roll... how about the computer in the same box as well?
seperated (not sealed) by a thin piece of tin?

I've got a nice big box the original controller came in, and would
like to re-use it and clean up the install by getting rid of the other
ugly boxes...

Thanks

Rod