Comment by numpad0

SLS printers lay a layer height worth of powdered metal and fuse it with a laser engraver. Thee bed lowers one layer and the process is repeated. They don't bring materials used like inconel to full melting temperature, only do what it takes for the metal sand to clump together. That's one source of pores.

I assume you can just anneal or print then recast in sand or whatever, maybe even lostwax with Al as wax, but the point is that porosity in a print itself is inevitable with current powder based tech.