the danger comes from the friction surfaces which get strongly charged up and can then deposit their charge onto nearby conductors via corona-discharge.
He should be able to get some idea about static charge buildup by turning out the
room lights [assuming nighttime, :-)], and rubbing his finger and various other
materials over the surface of the project. I am kind of surprised of how many
situations around the home where I've seen static sparks that way. Most notorious is moving the sheets on the bed. But I live in a very dry climate too. You never notice
unless it's pitch dark.