The recent increase in environmental challenges and concerns has enhanced global awareness, forcing a shift towards sustainable manufacturing to improve resource efficiency and reduce waste generation. Additive Manufacturing (AM) is considered sustainable, albeit in different ways depending on context and products. This study aims to shed light on AM adoption, highlighting how experts perceive the sustainability of AM, and this affects the selection of AM for part fabrication. A semi-structured interview revealed that experts have diverse perspectives on using AM, recommending or rejecting it for producing specific parts and identifying distinct sustainability hotspots. The hotspots classified under process sustainability were the most critical factors in process selection, followed by those about corporate and part (i.e., structure and geometry) sustainability. Overall, reducing the mass of raw material, reducing production time, part customizability, and surface quality resulted as the most mentioned factors within manufacturing process selection. Overall, AM was found to be more suitable than traditional manufacturing for process sustainability primarily due to time and cost, corporate sustainability for product customizability, and less for part sustainability due to poor finishing.