Chester

you need time to put away the gift before your sister enters and you need to be warned that your sister is coming
 * hang a bell to notify you that someone is entering and then put a door stopper to slow down the enterer you would hang the bell about 3" away from the door


 * put a trip wire to stop the enterer,
 * put a bucket on the door when it is open a few inches
 * put a buzzer on the door knob
 * use a spygear lazer alarm
 * put out a tripwire
 * buzzer under the doormat
 * put a horn under the door crack
 * put up a security camera
 * put an oil slick in front of the door
 * use a voicecommand system
 * put a finger scan lock

problems 3/10
different doorknobs

I decided to change the original design from a bell to a trip wire