Remote kill switch

I was wondering how do I build a remote kill swtch... I have a pretty good alarm, I'm doin this for if someone was to get my keys, I don't want a kill swtich I have to press a buttom everytime I get ready to crank the car, a kill switch that I can turn on/off with the push of a button(I was thinking about using a old valet switch/button)...how would I do this...I'm guessing I'm saying a normally closed kill switch in stead of a normally open

Are you looking for a remote kill switch?  So as to say if the car were to be already started?  Or a Starter disable switch?  So that the car cannot be started unless the switch is triggered?  It is going to make a big difference in the wiring of the switch.  If its a starter disable, you can use a normally open switch(such as old valet switch), and wire it to a relay as follows.#85. To 12v+.  #30. To starter side of starter wire.  #87. To key side of starter wire.  #86. To old valet switch.  And other side of valet switch to ground.  This way starter will not engage unless the old valet switch is pressed in and held during the start process.  Good luck.If it don't fit, Force it.

If it breaks, You needed a new one anyway!