The most powerful magnets you can lay your hands on reside inside a computer hard drive ( my day job is pc techie ).
Just grab a scrap hard drive and open it up. Be careful when removing the magnets, they are so powerful that they may clickback together and nip you.
If you don't have a scrap hard drive - just ask at your nearest computer shop, they will have plenty.
If you are anywhere near Morecambe, Lancashire you can collect as many as you like from me.
I would like to see this Revell Magic - let us know if it works.
see ya,
Vince