Partial CAD rendering of the Liebknecht ArchIn 1918, just after the end of World War I, Germany was in an uproar. Their citizens had just lived through four bloody years of war only to suffer defeat. The country was ripe for a revolution and it came in the form of Karl Liebknecht, the co-founder of the Communist Party of Germany.

In 1918 Liebknecht addressed the German citizens from the second floor of their old Privy Council building. He delivered an impassioned speech with phrases like, "Stop making bayonets which will be thrust into your entrails by the knights of the Government," and as he did he stood beneath a decorative arch. The archwould forever be known as Liebknecht's Portal because his speech sparked a wildfire in Germany. Eventually, the imperial government was replaced with a republic, but not before Liebknecht was murdered along with his partner, Rosa Luxemburg.

Today the Liebknecht Arch still stands and is a national symbol for the German people. The arch is so important they decided an exact copy should be built and put on display in the Berlin City Palace. Sculptors would be hired to create an exact replica of the arch in sandstone, but they faced one big problem. In order to create an exact replica of the arch, they needed exact information about the arch. Berlin-based 3D scanning specialist TrigonArt was contracted to scan the Liebknecht Arch and create a high-resolution printable model for the sculptors. The TrigonArt team took thousands of individual scans and pieced them together into a package including a complete high-resolution printable model and individual scans of important details.

Herm being scanned

The sculptors wanted to take the project one step further than virtual though; they wanted to hold real physical models of the pieces they were supposed to be duplicating. 3D printing provided the fastest and most accurate option for them. The sculptors sent TrigonArt's scans over to large-format 3D printer manufacturer Voxeljet, where it took them only eight days to print a replica of the entire arch out of sand. CEO of Voxeljet Dr Ingo Ederer commented, "The entire order was comprised of approximately 100 individual jobs, including moulds measuring 1.5 x 1.0 x 1.0 m. We can also use our large-format printers to print larger components with a volume of up to eight cubic m, but we left it at a maximum of 1.5 cubic m so as not to limit the handling of individual components."

Fitting around a hundred individual prints together into a life-size arch was no easy task, but in the end the replica was perfect. "The copy of the historic portal is geometrically indistinguishable from the original," organizers said. "Print quality, precision and detail of the sand moulds are beyond any doubt thanks to the impressive high-performance of the VX4000 printer. Now it is up to the sculptors, who use the 3D print as a template for their work, to sculpt a perfect copy of the Liebknecht portal in sandstone."

The Liebknecht portal isn't the only artifact that has been carefully resurrected in the last few years. King Tut's remains have been replicated and scanning is in the works for plenty of historical sites and museum pieces.