If you've got a spare minute you might want to try this 1 Minute Finger Tip. You'll need two small rectangles of card, two dice, some cotton thread, a ball point pen, a ruler, a single paperclip and a pair of scissors. When you're ready to go, start the clock and begin by marking a line that's 2cm in from the edge, on both rectangles of card. Do this using a ball point ben and ruler. Press hard so that you score the card and it is easily folded. When done, fold the card in like this. Next, take a pair of scissors and cut one rectangle of card diagonally from the corner to the middle. Now take the cotton thread and carefully tie one end onto a paperclip with a knot - then stop the clock! You've actually made an alarm for your bedroom. Here's how it works... Stick the two pieces of card to a wall by using sticky tack, to make a mini shelf, like this. Balance the two dice on the shelf and remember what numbers are on showing the outside. This is your secret code! Carefully thread the cotton out, without knocking the dice off. Tie a knot around your bedroom door knob... ...then carefully leave the room. To be able to do this you'll need to leave a little slack in the cotton thread so that you can crawl underneath... The next time anyone goes in your room they'll open the door and unknowingly pull the thread, collapsing the shelf and dislodging the dice. Even if they try to put the dice back they won't know your secret code, so you'll be able to tell that someone's been in. To complete the effect, why not add a burglar alarm box to cover your shelf and dice?