Wow, that is really nice!
Where did you get them, especially the cylindrical magnets with holes?
Simply search ebay or alike for "magnet 14mm 3mm hole". Separating force of these is around
3 kg when pulled vertically off steel. Mine are 14 mm in dia., 5 mm thick with a 3.5 mm hole.
If you can wait for the slow boat from china they are really cheap.
Then get some M3 bolts and M3
nuts as well as some round plastic spacers with a 3 mm hole. If required: for scratch protection glue
a thin piece of felt under each magnet. This reduces the magnetic force to a somewhat
more manageable degree.