Thin liquid sheet jet flows in vacuum provide a new platform for performing experiments in the liquid phase, for example X-ray spectroscopy. Micrometer thickness, high stability, and optical flatness are the key characteristics required for successful exploitation of these targets. A novel strategy for generating sheet jets in vacuum is presented in this article. Precision nozzles were designed and fabricated using high resolution (0.2 μm) 2-photon 3D printing and generated 1.49 ±± 0.04 μm thickness, stable, and <λλ/20-flat jets in isopropanol under normal atmosphere and under vacuum at 5 ×× 10−1 mbar. The thin sheet technology also holds great promise for advancing the fields of high harmonic generation in liquids, laser acceleration of ions as well as other fields requiring precision and high repetition rate targets.