The hardest stretch of this build looks like the 4th axis work: cutting clean facets, recesses and tapped holes into titanium on a vertical mill is unforgiving going. The maker handled it by finishing the turning first, then carrying the part over to the mill with a rotary axis fitted, holding the workpiece in a threaded fixture nipped up with an Allen key. Getting a grip like that on a titanium hub seems like a sensible way to keep things rigid for rotary cutting.
The flow of the job reads nicely. The lathe work came first, and the part was completed during a second lathe operation before heading to the mill. Once there, the cutter formed the facets and recesses and tapped the holes. The finished head carries radial threaded ports and takes a removable conical jet nozzle, so the hub ends up doing a lot of work in one compact piece.
A few details stand out to me. The whole assembly includes a central spring-loaded brass ring mechanism, which is a pleasant contrast in both colour and material against the surrounding titanium. The finished hub is mounted to a thick braided steel cable, and after being set on an arbor the part was inspected before moving on. That sort of check between operations is worth copying.
The one open item is scale: the maker still has roughly 10 unique components to produce for this mostly titanium sculpture. That is a serious amount of remaining work, though the completed hub has already been assembled and shown off outdoors, which suggests the hardest chunk is behind them.