The precision of the part cooling fan is largely a function of the ducting, not the fan. For that reason, this is a commonly redesigned part and findable on thingiverse/printables for most standard tool heads.
Alternatively, you are halfway to reinventing a CPAP (yes, like the sleep apnea machine). This is fairly common on high-end Ratrig and Voron builds. They were designed for enclosed printers where the air that a traditional part fan would use is already hot, so the fan gets moved outside to get cooler air and pumps it through a tube to hit the part.