First i made some from ABS. If the fan doesn't run fast enough, they start to melt when i print ABS with them.
Then my company made one from aluminium with an SLM printer :-D
Works much better. Only drawback is that aluminum leads the heat really good. So i have to check if the plastic around the SLM printed part doesn't get to hot.
The orange ones are made from extrudr ABS-X with my Prusa i3 Mk2.
The silver one is made from aluminium with an SLM printer.