This study presents a method for creating tunable afterglow in 3D-printed structures for mechanical self-monitoring. The researchers designed two organic molecules with a donor-acceptor-acceptor (D-A-A') configuration, which exhibit dual-emissive afterglow with tunable lifetimes (86.1–287.7 ms) when doped into various matrices. Using a photosensitive resin, they fabricated complex 3D structures through 3D printing technology, which can exhibit tunable afterglow lifetime and Young's Modulus by manipulating photocuring time and humidity levels. The structures show long-lived bright green afterglow without deformation under external loading when sufficiently cured or in dry conditions. The mechanical properties of the 3D-printed structures can be monitored and quantitatively manifested by afterglow lifetimes. This work opens new opportunities for constructing flexible 3D printing devices capable of sensing and real-time mechanical detection. The study also explores the photophysical properties of the molecules, including their emission characteristics and energy transfer processes. The results demonstrate that the mechanical properties of the 3D-printed structures can be manipulated by controlling photocuring time and moisture levels, with the afterglow lifetime serving as a quantitative indicator. The findings highlight the potential of organic afterglow materials in applications such as sensing, anticounterfeiting, data encryption, and flexible 3D printing.This study presents a method for creating tunable afterglow in 3D-printed structures for mechanical self-monitoring. The researchers designed two organic molecules with a donor-acceptor-acceptor (D-A-A') configuration, which exhibit dual-emissive afterglow with tunable lifetimes (86.1–287.7 ms) when doped into various matrices. Using a photosensitive resin, they fabricated complex 3D structures through 3D printing technology, which can exhibit tunable afterglow lifetime and Young's Modulus by manipulating photocuring time and humidity levels. The structures show long-lived bright green afterglow without deformation under external loading when sufficiently cured or in dry conditions. The mechanical properties of the 3D-printed structures can be monitored and quantitatively manifested by afterglow lifetimes. This work opens new opportunities for constructing flexible 3D printing devices capable of sensing and real-time mechanical detection. The study also explores the photophysical properties of the molecules, including their emission characteristics and energy transfer processes. The results demonstrate that the mechanical properties of the 3D-printed structures can be manipulated by controlling photocuring time and moisture levels, with the afterglow lifetime serving as a quantitative indicator. The findings highlight the potential of organic afterglow materials in applications such as sensing, anticounterfeiting, data encryption, and flexible 3D printing.