The COBOD concrete 3D-printing system passed a milestone recently with completion of a three-story residential building in Riyadh, Saudi Arabia. The structural walls were built up layer-by-layer using the additive manufacturing method, which is seeing wider use because of its relatively fast build times and customizable designs. The 9.9-m- (32.5-ft)-tall building was printed over the course of 26 days by Saudi-based real estate developer Dar Al Arkan using a COBOD 3D construction printer. COBOD uses a gantry-mounted, robotic 3D-printing system that can build up walls based on a pre-loaded design plan. The printer uses the proprietary D.fab concrete mixture developed by Cemex and COBOD.