Hunts did it at least 10 years ago. Not sure if they were the first. They have re-released the REvolution Turbo this year with similar technology. I have lots of nice Turbos in stock
Id like one done with a full carbo core (Like a golf club).Not sure it would work though...
Pretty sure GN Australia did it some 20 years ago with the GN Ultimate. This was the bat used by Boon, Slater and Hayden at the time.