You will need:
*Some pliers (i have these from jewellery making)
*A old butter knife
*Some old tweezers
*A old straightener
*your MAC eye shadows
Always use old tools or thing you don't mind that get damaged as the glue and heat can sometimes get a little messy.
I used a old straightener which is about 5 years old which i still have but don't really care too much for as the plastic can stick to the plates, if however you don't have a old one kicking around then you can use a wax proof paper between the eyeshadow and straightener plate to stop this from happening
Step 1: Start by taking your eyeshadow and tweezers or butter knife ( i personally prefer tweezers as their safer and easier as they fit rite in the gap) and by the opening theres a little gap where you need to push the tweezers in and just unclip it and pull the eyeshadow out of the packaging.
Step 2: Place the eyeshadow pan on the straightener using the pliers, i think pliers are the safest to place on and off as prevents any burns from happening, i have this on the highest heat setting as you can see as it old dirty and battered it doesn't heat up too hot so i think its best to use on highest but different straighteners will vary.
Step 3: You will start to see the metal pan come away from the black pan once you see this remove the eyeshadow with pliers and if you look underneath there should be a hole where you can push with the butter knife to push the eyeshadow out of the pan, if it doesn't come away with ease don't force it as you may damage the eyeshadow just place back on heat until ready
Step 4: This is the mess you should end up with one pushing the butter knife underneath and lifting the shadow you will need to put the knife under the metal plate to release the eyeshadow from the black pan as below
Step 5: A, If your wanting to place magnets on the bottoms then leave to cool as the metal pan is really hot so be careful and then this is when you would put on the magnet and place in pallet
I don't use magnets once my eye shadows are in i don't really need to change them around so i prefer to stick them in.
B, Whilst the glue underneath is still tacky as it will be from the heat i put it straight into the MAC pallet to re stick and cool in there, if the glue has completely gone you made need to add some glue. this method has never damaged my eye shadows or my pallet and works the best for me.
Once done you will have your pallet ready to use i will do a separate post on my pallets so everyone can see how i organise them and the colours i have
Hope this helped