i'm not making a cardboard, i found some but not spherical ( bought them anyways because they are fun), for my experiment the magnet is the key component i didn't get the magnet so i didn't look for any other components, besides i think anything else is easy to find i need a spherical glass ( with a to be calculated radius depending on the radius of the sphere magnet) some copper coils a transformer , a small motor and some water.
the not spherical magnets are found at a place called Ktrangi in jneh area if you're interested.
PS: to my knowledge a cardboard is this :
http://en.cardboard.com.ua/images/stories/img/cardboard-boxes.jpg
what do you mean by making a cardboard with a magnet ?