A Lightweight, 3D‐Printable, Low‐Cost, “One‐Click” Dorsal Skin Window for High‐Quality Long‐Term Multimodal Subcutaneous Tumor Imaging

Intravital microscopy (IVM) using dorsal skinfold chambers (DSCs) enables real-time, high-resolution imaging of the tumor microenvironment. Conventional, metal-based DSC systems often cause animal distress and require technically demanding surgical implantation. To address these challenges and adhere to the 3Rs principles of animal welfare, this study presents a novel, stereolithography (SLA)-based, 3D-printed DSC featuring a lightweight (0.69 g) biocompatible resin structure and a suture-free "one-click" fixation system. This affordable device simplifies surgical installation and minimizes postoperative inflammation, allowing continuous multimodal imaging-IVM, micro-CT, ultrasound, and in vivo fluorescence-for up to four weeks. The system is validated in mice bearing subcutaneous tumors generated from PDAC93-GFP pancreatic tumor organoids implanted in the DSC. Longitudinal, high-resolution imaging successfully tracks tumor expansion, active stromal remodeling characterized by progressive collagen fiber compaction and alignment, and the emergence of a highly tortuous peritumoral vascular network. Furthermore, in vivo tracking in Catchup mice reveals a distinct transition of tumor-associated neutrophils from random acute inflammatory migration to directed tumor-driven chemotaxis. Overall, this ergonomic and robust DSC design provides a highly reliable platform for sustained, high-quality assessment of tumor-stroma-immune interactions and therapeutic responses, while notably improving animal welfare.