If you're sintering it, it's got effectively none - you're fusing powder and the unfused powder goes back in the hopper.

That was the original thought... but turns out the powder thats was near the laser gets affected by the heat and if you pour it back in you get all sorts of additional material oddities in the next part. So you get get material properties for the first part but the scatter kills you on part #2.

Idk why you would make 3D printed heat sinks... probably because you have too much money but ok it works fine in any application where you dont need structural material properties. So if you want to turn a 10c heat sink into a $5 one you can or if you need some sort of fancy decorative shape for a trim price, great but the technology is decades out for practical and cost effective structural applications. You will see this stuff pop up here and there as peoples pet projects or to show how cutting edge some company is but its just not ready for prime time, and may never be.

I should caveat that all by saying that 3d printed parts like this should be great for fluid systems applications. Any time you need weird mixer geometries with internal cavities, probe holes, flow reducers and mixers 3D printed parts like this will work great.