What you'll need:
-A flat iron
-Palette you want to put shadow in
Here's how to do it:
Turn your iron on to its highest setting. Use wax paper to prevent the plastic from the compact from melting on to your iron. Then place your compact on it, this takes about ten minutes for the plastic to melt. Your shadow won't melt, and the formula won't change so dont worry! When you see the eyeshadow popping out a bit, its time to turn the iron off. Let your compact cool down before you remove the eyeshadow pan!
This is how it should look like when done
Now you can put them in your magnetic palette:)