Printing large-scale parts (over 50 cm) using 3D printing can be a challenging task, but there are several technologies and methods that are well-suited for this purpose. Here are some of the best technologies for 3D printing large-scale prototypes:

Fused Filament Fabrication (FFF) / Fused Deposition Modeling (FDM):

FFF or FDM 3D printers are widely available and can be used to create large parts by layering thermoplastic filaments. Large-format FFF/FDM printers with build volumes exceeding 50 cm in at least one dimension are available for industrial use.

Stereolithography (SLA):

SLA is a resin-based 3D printing technology that uses a liquid photopolymer resin cured by UV light. While it’s more common for small to medium-sized parts, some industrial SLA printers have larger build volumes suitable for larger prototypes.

Selective Laser Sintering (SLS):

SLS uses a laser to sinter powdered materials (typically plastics or metals) layer by layer. Some industrial-grade SLS machines can produce large parts, including those exceeding 50 cm.

Binder Jetting:

Binder jetting is a powder-based 3D printing process where a liquid binder is selectively deposited to bind powder layers. Some industrial binder jetting machines are capable of producing large parts.

Large-Format 3D Printers:

Some companies specialize in building large-format 3D printers specifically designed for printing large parts. These machines often utilize FFF/FDM technology with modifications to accommodate larger print volumes.

When choosing a technology for 3D printing large-scale parts, consider factors such as material requirements, precision, speed, and cost. It’s essential to select a technology that aligns with the specific requirements of your project and budget.

Additionally, as 3D printing technology continues to advance, more options for large-scale printing are likely to become available, so it’s a good idea to stay updated with the latest developments in the field.

For 3D printing large-scale parts over 50 cm, several technologies and printers stand out:

1. **Creality CR-10 S5 Plus 3D Printer**: With a large printing bed of 500x500x500mm, it is suitable for large-scale projects and offers features like a resume-printing function after power loss. It comes partially pre-assembled for easy setup.

2. **ANYCUBIC Chiron 3D Printer**: Offers a 400x400x450mm printing space and requires some effort in bed leveling and settings adjustments, but users report high-quality results even for prints that take over 300 hours.

3. **Creality Ender 5 Plus 3D Printer**: This printer provides a large build plate of 350x350x400mm and comes with an automatic bed leveling sensor, bed stabilizer, color touch screen, and easy assembly, making it a good option under $1000.

4. **Snapmaker 2.0 Modular 3-in-1 3D Printer**: Targets advanced users with a printing capacity of 320x350x330mm and additional capabilities like engraving, cutting, and CNC carving, suitable for professional and industrial use.

5. **SUNLU S8 3D Printer**: An affordable option that offers a print bed of 310x310x400mm and features like filament runout detection, a Z-axis dual linear rail, and a resume printing function for power failures.

6. **LONGER LK1 3D Printer**: This is an entry-level printer with a 300x300x400mm printing area, which is a great option for those who are new to 3D printing and looking for a cost-effective machine.

These printers are among the best options for large-format 3D printing and cater to a range of user levels from hobbyists to professionals.