This document outlines the steps with regard to aspects of design to conduct and run a round robin study (RRS) to assess the degree of variability in an additive manufacturing material or process. The RRS can be used to study variations arising from the AM production process including feedstock, machine operation, process control, and post processing. The RRS plan can identify various aspects of the AM process to be considered to execute the study so that it is possible to maximize the consistency of the results based on the objective of the study. Additive manufacturing is still a developing technology and round robin studies play an important role to help generate the information needed to populate materials engineering databases, determine design allowables, and improve processing and post-processing consistency in order to drive maturation. The result of the RRS is a qualitative or quantitative assessment of the material used or the process variability, rather than the assessment of accuracy and precision of a specific test method from an inter-laboratory study. Additionally, RRS can involve other entities besides laboratories. Round robin studies differ from normal research studies by having different participants, each trying to undertake a nominally identical process. The aim is to determine the effect of the desired variables on the process outcome. The output can be used for different applications such as the demonstration of process robustness or for derivation of material property data. A well-conducted RSS does not guarantee small variability, but ensures that any observed variability is indicative of the material or process, not poor study design.