<p>Internal temperature measurements are vital for the development in the industrial, electronic, and aerospace fields for a variety of applications, from heat exchangers to material selection. Specifically, advancements in additive manufacturing and 3D printing have enabled these fields to rapidly prototype and produce complex geometries at much lower costs. However, these designs will require testing and validation via internal temperature measurements before widespread use, which is further complicated by the increased complexity. These internal temperature measurements will ideally have spatial and temporal resolutions to aid calculations such as heat transfer. This study proposes a temperature-sensitive resin (TSR) by combining a commercially available 3D-curable resin with a thermographic luminophore and demonstrates that the TSR layer is temperature sensitive. It is demonstrated that the TSR can be used with a commercially available 3D printer and that testing equipment can measure the internal temperature along a 2D slice of a 3D-printed model by monitoring luminescent output. This temperature-sensitive resin and measurement technique, if further developed, may provide internal temperature measurements with high spatial and temporal resolution for potential use in the development of items such as heat exchangers, microfluidic devices, and aerospace bodies.</p>