Jeff, we do very exotic coatings at my work. DLC isn't really all that exotic, but we can do that. Usually we lay down a few hundred angstroms for extreme scratch resistance, so 2-4 microns like what is suggested for the forks seems excessive. I'm personally interested in this, so I'll ask a few of the coating scientists if depositing DLC on buckets with our equipment is plausible. Height is usually the biggest limiting factor in our coaters.