Although I intended the machine that Mekanik has linked to for mainly wood and maybe aluminium, I have recently been machining steel with it. Not the ideal machine, but using a small cutter (because of the high minimum spindle speed - I can run a 2.5mm cutter at 5000 rpm) I have been able to make profile cuts in 3mm mild steel. DOC is typically 0.2mm but that mainly because of the fragile cutters. I have just ordered some short series carbide cutters which should be much stiffer.

This is more "getting away with it" than using the machine within its comfort zone but it says something about the gantry design.