Garage Bay 3D printer for large objects
For such a device, I'd like to make a modular head with a lot of potential interchangeable heads:
1. All the typical FDM
2. Milling for CNC type operation.
3. Laser for cutting
4. MIG welding head
5. Arm with gripper for auto-assembly
6. Scanner head
7. FDM using atypical materials, such as dry slurry epoxy (with microspheres or flocked cotton)
Combine this with mobile robot arms to manage work pieces, and you're coming close to a complete fab lab.