It is easy to do a BCDK DIY with stuff from halfords but it will not do the job as you need the end connector cone peice to cover wider surface area. See below
I looked into this and the hard part is getting the hose to connect to near the brake disk.
That's why i spoke to RJN because theirs has the collecting duct at the front bumper and a funnel-shaped cone at he brake end of the hose to dissipate the heat unlike the stillen kit.
Bennet, do you have any more pics of the disk end of the connection?
No, these were all from Stillen's site
Other examples below:
example of SS cone at the left of pic
Double ducts
5zigen 350z cooling duct(for oem size disc)
Nice