We report on a fused deposition modeling 3D-printable rotary valve fabricated from high-grade plastics such as polyether ether ketone or lower-grade plastics like polylactic acid. The valve weighs less than 90 g and has the potential to be integrated into portable and autonomous chemical analysis systems. It has been demonstrated to be leak-proof up to 2.75 bar (40 psig). The valve operates on a 5 V power supply and can be controlled via USB cable or I2C communication. The cost of the valve, including electronics, when printed from high-grade plastics, is less than 100 USD per piece.