Purpose A useful potential application of additive manufacturing (AM) techniques is in automated assembly of existing discrete parts via printing of new material onto two or more parts simultaneously to form joints between them. The purpose of this paper is to explore the concept of extrusion-based AM for automated assembly, examine potential concerns and perform validation to test the feasibility and value of such an assembly method. Design/methodology/approach To validate the theory and address potential concerns, six factorial-designed sets of joined ABS, PETG and PLA samples were manufactured and tensile tested. Each set contained two replications of four samples and was a unique part-joint material combination. To better interpret the results, a new static material characterization was completed on the materials used, as well as joint tests using four mechanical and chemical methods for each material. In total, 69 test articles were examined. Findings The tests showed that the joints were effective and strong, even under the inherently eccentric geometry. While there was some variance between replications, in almost every case, the AM joints were found to be equal or superior to those made by traditional methods. ANOVA showed variance in which factors were significant between sets, but all cases were shown to satisfy the Fisher Assumptions at a significance of a = 0.10. Originality/value This paper develops and validates a new application of extrusion-based AM. When developed further, this application is expected to increase the commercial application range and industrial efficiency of fused deposition modeling and AM in general. The results of this study should provide a link between traditional automated assembly methods and AM. This paper also provides some original AM material characterization data and observations on material behavior under eccentric loading.