Graphene spray and ...

most likely a vacuum chamber and ultrasonic spray system.

PTSS:

Assuming it's not all BS I assume that they use an ultrasonic spray process (don't know how you came up with HT ovens regarding this method).

Also, considering the conductive nature of the Graphene I would not be surprised if the cone material receives a static charge in order to better/more uniformely attract the conductive Graphene mist.

Such charges are used with metal as well as ceramic plating, and I don't see why it would not apply here as well.

Otherwise, ask the manufacturer,

Deekay, I too would have been skeptical if there wasn't so much interesting
literature on this most recent use of the same carbon that's in common lead pencils.
Your ideas on application are not unreasonable but a little research will reveal the
unusual and difficult processes involved that I came across to create graphene. That's why I'm very interested in how Magico claims to have coated their driver with graphene.

Maybe, just maybe, Magico copied the technique Synergistic Research uses to coat the Black fuse with Graphene.