I'm attempting to build a disco light with 4 lightbulbs powered by mains power, controlled by a microcontroller. At the moment, I'm trying to figure out what to use for the housing. I know a plastic case would work well, but all the plastic cases I have all have non-ideal dimensions, whereas some shoeboxes I have would be perfect. I tried looking up the dielectric constant of cardboard, but the closest thing I could find was the dielectric constant and dielectric breakdown voltage of paper, but different sites had values on different orders of magnitude. I'm guessing this is because of the different types of paper that exist. I'm inclined to go ahead and do it because I know lightbulb screw shells are insulated from the outer metal casing with cardboard, but I thought I should check. Can cardboard insulate against mains voltage?