This is an experimental feasibility study. The objective was to analyze the potential of open-source freeware (OSF) to train residents in virtual surgical planning (VSP) and compare this workflow with commercially available software (CAS). A workflow for mandibular reconstruction with a fibular free flap (FFF) was developed in 3D-Slicer and Blender and compared to our clinical workflow in Materialise Mimics Innovation Suite version 25 (Materialise InPrint, ProPlan CMF and 3-Matic). Five CMF residents, inexperienced in VSP, were trained to use both the OSF and CAS workflows and then performed four planning sessions on OSF and CAS. The duration (minutes) and the amount of mouse clicks (MCs) of every step in the workflow were recorded. Afterwards, the experience with VSP was investigated with the System Usability Scale (SUS) and a self-developed questionnaire. The total VSP time with CAS took 91 ± 15 min and needed 2325 ± 86 MCs compared to 111 ± 26 min and 1876 ± 632 MCs for OSF, respectively. The questionnaire had an 80% response rate. The SUS for CAS was 67.5 compared to 50 for OSF. The participants believe it is extremely valuable to learn VSP during their training and to be able to perform VSP as a surgeon. We believe OSF can be a cost-effective alternative compared to CAS for the training of surgical residents to gain insight in complex surgeries and to better understand CAD limitations and possibilities.