But here's the question.. does your egg have to be conductive or magnetic? Why not aluminum, which is still cheap, also easy to machine or cast.
I once machined an aluminum egg for Harry Goldman to use in his Egg of Columbus machine. The egg refused to spin up to a vertical position. It spun but stayed on it's side. I don't know if that's because I didn't make the shape just right, or if the machine lacked enough power. Harry suggested that a lot of power was needed to deal with a heavy solid egg. Harry had good success with various hollow eggs of aluminum. I forget if he tried other metals.John