Background: Here we present an open-source solution, comprising several 3D-printable mechanical pieces and software tools, for frameless stereotaxic targeting in young and adult pigs of varying weights.New metbod: Localization was achieved using an IR camera and CT imaging. The positions of the tools were followed, after registration of the pig stereotaxic space, with a CT scan and open-source brain atlas. The system was used to target the lateral ventricle and the subthalamic nucleus (STN) in one piglet and two adult Yucatan miniature pigs, which were either normal weight or obese.Results and conclusions: Positive targeting was confirmed in the first trial for all subjects, either by radiopaque CT enhancement of the ventricle or actual recording of the STN electrophysiological signature. We conclude that open-source freely available models, easily built with low-end 3D printers, and their associated software can be effectively used for brain surgery in pigs, at a minimal cost, irrespective of the weight of the animal.