Parts up to 900 mm. Industrial printers. Segmented assembly.

Single-part maximum: 914 × 610 × 914 mm in industrial FDM (Stratasys F900 class). Single-part SLS: 700 × 380 × 580 mm. For larger parts, segmented approach: split design into sections that fit build envelope, print separately, bond with epoxy or ultrasonic welding. Common segmentation joints designed to be invisible in final assembly. Realistic practical limit: 2-3 meters depending on part geometry and assembly complexity.

FDM large format: cheaper per volume, layer lines visible, lower dimensional accuracy (±0.5 mm), slower print time. Best for: architectural models, visual concept parts, tooling where finish doesn't matter. SLS large: smoother finish, better accuracy (±0.3 mm), faster per volume for batch of parts, more expensive. Best for: functional large parts, cosmetic large parts, production-intent prototypes.

Modern segmented 3D printed assemblies can have nearly invisible joints. Techniques: (1) Design segmentation joints at natural break points in geometry. (2) Use dowel pins for registration during bonding. (3) Epoxy or ultrasonic welding for permanent joint. (4) Post-assembly sanding and finishing across joints. Automotive body panel prototypes commonly assembled from 4-6 segments with seamless appearance.

Single-part large FDM: 3-5 days (long print cycles). Large SLS: 3-4 days. Segmented assembly (4-8 sections): 2-3 weeks including assembly. For urgent large prototypes, parallel printing and assembly can compress timeline. Schedule early for large programs — build capacity for large parts more limited than standard.

Large format 3D printing expensive due to: long print time, large material consumption, specialized equipment. A 800mm automotive body panel prototype: $2,000-8,000 depending on complexity. Compare to: CNC equivalent might be $5,000-25,000 or impossible due to size limits. 3D printing often most economical path for large prototypes.

Large parts often have anisotropic properties — weaker in Z-axis (build direction) than in XY plane. Design for this: orient critical load directions in XY plane, avoid Z-axis tensile loading, use lattice infill for interior structure. Full-density print throughout large part not economical — we design with strategic infill patterns that maintain strength where needed.