A minimal cost CNC Machine with the goal of some basic aluminum capabilities and easily swap out the functionality. The only special tools needed are a hacksaw, and a drill to for 4 holes. This can be easily expanded to almost any length, width, and depth depending on rigidity required. This is built using commonly available aluminium or stainless steel tubing. Most woods and plastics should be no problem. It milled Aluminum with a footprint of 60x80x10 cm.
You can switch the spindle out with a drag knife, laser, Extruder, ect, making it a great prototyping multi-tool. By adding length and depth It could easily be used to shape large easily milled things like wood, foam, or plastics. Keep it small for aluminum.