The signal of magnetic resonance imaging (MRI) can be enhanced by several orders of magnitude using hyperpolarization. In comparison to a broadly used Dynamic Nuclear Polarization (DNP) technique that is already used in clinical trials, the para-hydrogen (pH₂) based hyperpolarization approaches are less cost-intensive, scalable and offer high throughput. However, a pH₂ generator is necessary. Available commercial pH₂ generators are relatively expensive (10,000–150,000 €). To facilitate the spread of pH2 hyperpolarization studies, here, we provide the blueprints and 3D-models as open-source for a low-cost (< 3,000 €) 50 bar liquid nitrogen pH₂ generator.