Before taking on this project our fridge was covered in those magnets they send along when you order a pizza. Why I stick them on the fridge instead of throwing them away, I'm not sure. After using a button covering kit for my headboard project, it was incredibly easy to figure out how to make magnets. So much more attractive than pizza magnets.
Cover button tool and flat back buttons
E6000 or hot glue gun and glue sticks
Cover some buttons. (If you need help see this tutorial).
Using the flat back buttons are a little tricky (or at least they were for me) because there are no loops to show you which side should be facing up. Make sure the indentation is facing up and not down. I was having a hell of a time until my bf pointed out that I was doing it the wrong way.
Apply a glob of glue to the back of your covered button and press on a magnet. (I used super heavy duty 3/8" neodymium magnets but regular magnets will work just fine too.)
Three great places to buy cover buttons are coverbuttons, FiddlersCreekDesigns and everythingribbons
I bought my heavy duty magnets from DancingMagpieSupply. Or you can by regular magnets from jcaroline.