Let the fun begin !!! ???

[EddyCurrent]

Regarding metal work, I think you have it sorted with respect to 3D carving, i.e. adjustable height bed, 4th axis option.
Have you thought about how the 4th axis will physically attach to the frame ? and will material held in the chuck be parallel to the X plane or the Y plane ?
I'm thinking about a 4th axis myself but there's no room in my control panel for the gear, but thinking about it I feel it would be best as a stand alone unit with control wiring back to the main panel via plug & socket.