I've got a lot of those little Neodymium magnets that I use. You really need the latch magnets both to make the fixtures and for basic building. The square shape of them let you use them to butt up against parts. And you really need all 4 latch magnets on a fixture in order to hold in place. Trust me on this one. The little Neodymium magnets are great for holding the plans secure on the steel sheet.

Ken