I am not sure what “blueprint technique” is referring to, but putting wood dowels in the tips of shafts on irons is nothing new. I did it 30 years ago to deaden the feel of my irons. That is the only reason, that I have seen, to do it. I have also put wooden dowels in the butt of steel shafts for the same reason. We didn’t have specific inserts designed to go into shafts, or have shafts with feel dampening inserts in them like we do today. I have also used rubber inserts in the tips. The wooden dowels were small and didn’t weigh much, so the swingweight or overall weight of the club was not affected. Anything you put into a steel shaft, from rubber, to wood, to cork, to something like the ProSoft inserts we carry (PS5000), will dampen the low frequency vibrations that occur in steel shafts at impact. The affect of small wooden dowels in the tip or butt would be less than something like the Pro Soft inserts. With regards to graphite shafts, inserts make no sense if the reason is to dampen vibration. The characteristics of composite material (graphite and resin) that graphite shafts are made of naturally reduce vibration.