CRISP: A 3D printer-based platform for precision solution printing on paper-based substrates

The scalability of self-driving labs is currently limited by the high cost of automated liquid handling. To address this, we present a low-cost, open-source platform designed to function as a 'frugal twin' to serve as a programmable hardware node in automated labs. To do this, we modified a commercial Ender-3 3D printer to print solutions on flexible paper-based substrates using a custom syringe pump assembly. Our printer, CRISP (Controlled Robotic Inkjet Solution on Paper), is driven by the Ender's native stepper motor and G-code infrastructure, and dispenses reagents via disposable pipette tips. Our demonstration with printed dyes shows a reliability of 96.8% and 98.2% for positional accuracy and uniformity of droplet circularity, respectively, confirming the system's potential as a reliable low-cost module for automated research.