The perfect copy of a historic monument

It was an unusual request for the voxeljet service center: Printing 100 sand molds at sizes of up to 1.5 cubic metres. 

This large order is related to the reconstruction of the historic Liebknecht portal - a very unusual project, as two versions of the portal will now be located in Berlin in the future: the original in the former Privy Council building of the former German Democratic Republic, and a 1:1 copy in the Berlin City Palace that will be built. 

The idea behind this unique project: A desire to retain the originality and historic significance of the Privy Council building, while at the same time bringing the Liebknecht portal to the new palace – a project that can only be implemented with a copy that is true to the original.  

The challenge with this project was to prepare an exact template for the sculptors, so they could begin with the production of the copy. Conventional lamination techniques could not be considered since the original portal had to be handled very carefully. Instead, those in charge decided on a particularly innovative copy method: the touch-less 3D scanning of the portal and subsequent physical creation of the portal using the 3D sand printing method.

Berlin-based scan specialist TrigonArt is one of the leading companies for these types of projects. The competent 3D measurement team prepared a three-dimensional scan of the object and created an entire high-resolution model of the portal out of the individual scans. In addition, specific areas such as the herms and geniuses were produced as individual 3D models and prepared for physical production purposes. The subsequent creation of the physical models using 3D printing was the task of the voxeljet service center in Augsburg. 

A review of the data showed just how extensive and complex the printing job would become: "The entire order was comprised of approximately 100 individual jobs, including molds measuring 1.5 x 1.0 x 1.0 metres. We can also use our large-format printers to print larger components with a volume of up to eight cubic metres, but we left it at a maximum of 1.5 cubic metres so as not to limit the handling of individual components," says voxeljet CEO Dr. Ingo Ederer. In the case of the large molds, cut-outs for transport rings were made in the 3D print, which greatly facilitated logistics. These cut-outs can be easily closed with the corresponding plugs. 

The result of the innovative copy process met the expectations of all those involved. The copy of the historic portal is geometrically undistinguishable from the original. Print quality, precision and detail of the sand molds 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 sand Stone.


Technical data

Total size 7,000 x 4,500 x 1,300 mm  Total size 6,310 x 1,880 x 1,850 mm
Weight 5,800 kgWeight 2,770 kg
Individual pieces52Individual pieces32
Material SandMaterialSand
Layer thickness0.3 mmLayer thickness 0.3 mm
Lead time 25 daysLead time 25 days
Build time 12 daysBuild time 8 days