One of the advantages of friction stir welding (FSW) is that no filler material is required to make a weld. However, this can also be a disadvantage as additional considerations are required to overcome issues with component ‘fit up’ and alignment in production. Adding material to the weld can aid production issues and also be used to add different materials into the weld to alter the properties and add features to components. This technique is called ‘AdStir’. Figure 1 shows two AdStir examples: a) forming a radii in the internal corner and b) depositing a local feature.