Introduction: Custom built fenestrated endografts are the preferred option for treating complex paravisceral abdominal aortic aneurysms (AAA). However, when resources and time are unavailable surgeon modified endografts (SMEG) have been reported to be a safe and effective solution. Creation of fenestrations is approximated based on measurements of the physician using imaging software. We sought to determine the applicability of 3D printing a patients' aortic segment in achieving perfect matching of fenestrations with target vessels in SMEGs and to detect factors affecting time needed to achieve this for urgent. Methods: The same vascular surgeon/operator used free open-source software (3DSlicer, MeshMixer) and contrast enhanced computed tomography (CT) series to manually segment the celiac to renal arteries part of the aorta and the first 3 mm of each branch. This volume was then transformed into a hollow 1:1 sized model to be printed with a fused deposition modelling printer (Prusa MK3S). Dedicated 3D-printer software was used to calculate estimated print time with sterilizable co-polyester filament (nGen Flex, ColorFabb). The time for each step of the procedure was recorded along with the 3D model dimensions/volume and filament volume used, CT characteristics and patient details. Continuous variables are expressed as mean +/- SD. Kendall's tau multiple correlations and multiple linear regression were employed to seek relationships between variables and detect independent predictors of time taken. Results: Thirty-one consecutive AAA patients' preoperative CTs were analyzed (7 juxtarenal, 24 infrarenal, 29 men). Each patient's hollow 3D aortic model segmentation needed 13.5+/-4.3 minutes while preparation for 3D printing took 1.3+/-0.9 minutes. Print time was calculated to be 131.3+/-35.2 minutes. Segmentation time displayed a negative correlation with the number of CTs previously segmented by the operator (b = - 0.484, p< 0.001). Print time showed a positive correlation with filament volume (b = 0.6, p< 0.001) and 3D model volume (b = 0.406, p=0.001). 3D model volume was also found to have a positive association with CT interslice distance (CTID) (b=0.628, p< 0.001) and a negative relationship to female sex (b=-0.329, p=0.03). Multiple regression analysis indicated that segmentation time was independently predicted (R squared =0.849, p< 0.001) by CTID, maximum Hounsfield value of the segmentation, number of CTs previously segmented by the operator and the height and sex of the patient. In turn, print time was independently predicted (R squared =0.945, p< 0.001) by filament volume, model dimensions, CTID and the height and sex of the patient. Conclusion: Free open-source software and 3D printers can be used to perfectly align fenestrations on surgeon modified endografts by deploying the endograft within the sterilized 3D printed aortic segment of each patient in an ideally short time frame for urgent cases. Besides aortic volume printed, operator experience and small CT interslice distance can independently reduce time needed.Figure 2Visceral Aortic segment model - top view.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Disclosure: Consulting / Proctoring regional Endologix distributor