There are resort specific magnets. I have one from each resort we have stayed at since DD was born on our refrigerator (WL, Poly, GF, and BC). I know the WL one is total rubber and I have never had a problem with it falling off the refrigerator or curling up. I don't think any of the resort pins are metal. I also have a 4 parks spinner that we like to walk by the refrigerator to spin and see which park we should be in if we were at WDW that day. That one is metal. You will find a ton of magnets at WDW. I did have one rubber one from DL that is the Mickey crew that curls up and slides. Most places were you can buy magnets, you will find them either sticking on a metal post or piece for display, or you will find metal somewhere in the area or in the store where you can stick them to see how they do. I would just say be sure to do that before you buy. There was a rubber Minnie one I really liked one year, but it was sliding and not holding when I put it on metal there. Also when we got the BC one last year, I know that I was playing with them, and there was one that was not holding very well, but the others were fine- so I bought the one with the strongest hold. You will definitely have a lot to choose from!
As far as turning Disney pins into magnets- you could bend and break off the pin post and glue a magnet onto them. We have had a pin or two that much to our dismay the pin post broke off. You might have to file it down after you break off the pin post to get the magnet to lay flat, or place the magnet under where the pin post was, but it could be done.
Thanks for the warning! I like those 3d plastic ones too. I have a Hogwart's Crest one that I LOVE. Would have been great to have a "matching" 4 parks magnet. I'd be willing to reinforce it with a heavier duty magnet at home, but not if it is curling up!!
