Additive Manufacturing-produced prototype, redesigning a crucial piece of the Tropospheric Monitoring Instrument (Tropomi) atmospheric spectrometer instrument set to fly on ESA’s Sentinel-5P mission in 2016. The original optical-quality mirror design, manufactured in aluminium with a mass of 284.6 grams with a nickel phosphorous coating, was remade with selective laser melting using titanium. The resulting part was streamlined, with unnecessary mass removed. In the event it weighed in at just 127.7 grams, with the same coating. This led to a mass reduction of 54%, despite using a 50% denser material, and was achieved with no reduction in optical performance.