Additive manufacturing (aka 3D printing) in metal or composites is great but still in its infancy, though progressing rapidly. There are great new technologies out there though most rely on some kind of sintering. Ultimately, they are still very expensive. If it were a tiny part, sure. But that pipe could quickly run into the very many hundreds of dollars, if not over $1k (at least for metals). And again, it's unlikely to give you the surface finish to allow for proper sealing without going through a secondary operation, which adds more cost.