Maybe this could be useful for you:
What I did was buying a toolbox (I'm sure they have those in Sweden

) which I can lock. So I put all my magic stuff in there, including my ID, and locked it up securely. Always have the key with me and the extra key hidden in some safe place.
My box is even in a nice 'suitcase' kind of shape
So now my little brother has stopped sneaking into my room and searching for the cards with which I can levitate a match
Oh and store the box in a high and/or hidden place so especially little children can't reach it.
Greetz