Are you trying to put a magnet on the bottom of the plastic base, such that the magnet will come in contact with the table (or other surface)?
If so, that's not hard to do. Just roll a wee ball of green stuff, press the magnet a ways into it, put the
GS ball + magnet into the hollow of the base, flip over, and press down (against a table). It'll be perfectly flat and you can add a dab of superglue once the
GS cures, if you want.
Edit - Hah! you ninja'd me
BC 
Great minds think alike?