Methods, apparatus, computer programs and non-transitory computer readable storage mediums for manufacturing gas shields for welding one or more articles

A method of manufacturing a first part (e.g., gas shield 62 for welding one or more aerospace articles 141) uses first data defining surfaces of the articles 141, 142, 143 to generate second data defining surfaces 621, 622, 623 of the first part 62, and then controls a three dimensional printer to print the first part 62 using the generated second data. The scanned first data from the articles 141 may be analysed to determine locations for receiving fixtures (66, fig 5) of the gas shield 62 to help coupling to the articles 141. Exhaust gas apertures 64 may help gas escape from the gas shield 62. A bespoke ALM gas shield 62 may snugly fit between aerofoils 142, 143. A controller generates data for surface 621 of the gas shield 62 using the data of the surface of the disk 141, data for a first side surface 622 using data from a side surface of the aerofoil 142, and data for a second side surface 623 using data from the aerofoil 143: surfaces 621, 622, 623 of the gas shield 62 have gradients matching surfaces 141, 142, 143. A controller may generate second data to 3d print a fixture or mask for cold spraying or for metal spraying processes. A CAD computer program may be stored on a non-transitory computer readable storage medium.