A 3D-printable mason jar net cup designed for hydroponic using the Kratky method. What is the Kratky Method? The Kratky method is the simplest form of hydroponics. A plant sits in a net cup with its roots reaching down into a nutrient solution. As the plant drinks, the water level drops, exposing part of the roots to air. This air gap provides oxygen to the roots while the submerged portion continues to absorb nutrients. No water changes or circulation needed — just set it and let it grow.