The maximum size of your parts depends on the material and manufacturing process you choose to have your 3D-printed or CNC-machined parts produced in.

All CNC Materials (Mill, X,Y,Z)
1828mm x 500mm x 152mm (72″ x 20″ x 6″)

All CNC Materials (Lathe, D,H)
152mm x 394mm (6″ x 12″)

PLA (Fused Deposition Modeling, X,Y,Z)
300mm x 300mm x 300mm (11.8″ x 11.8″ x 11.8″)

ABS (Fused Deposition Modeling, X,Y,Z)
406mm x 355mm x 406mm (16″ x 14″ x 16″)

PETG (Fused Deposition Modeling, X,Y,Z)
300mm x 300mm x 300mm (11.8″ x 11.8″ x 11.8″)

Nylon (PA 12 and PA 12 Glass Beads) (Multi Jet Fusion, X,Y,Z)
380mm x 284mm x 380mm (15″ x 11.1″ x 15″)

Nylon 12 (Selective Laser Sintering, X,Y,Z)

700mm x 380mm x 580mm (27.5″ x 15″ x 22.8″)

All Vero- Materials, Rubber-Like, ABS-Like, Multi-Material (PolyJet, X,Y,Z)
490mm x 390mm x 200mm  (19.3″ x 15.3″ x 7.9″)

Accura 25 (Stereolithography, X,Y,Z)
254mm x 254mm x 254 mm (10″ x 10″ x 10″)

Urethane Casting (may depend on material and geometry, X,Y,Z)
2200mm x 1200mm x 1000mm (86.6″ x 47.2″ x 39.3″)