So.... I've got lots of imperial bastions that I'm thinking I'm going to assemble. I was thinking though, about magnetizing the base, the roofs, and each of the levels so I can make them as large or as small as I want with the different games. Any advice? I've never magnetized anything. Should I do it before the paining? Do it after the painting? Where do I get magnets? How powerful should they be to prevent parts falling off during play? I'm thinking 4 magnets.. one per corner.