If you enjoy this project, then I encourage you to buy my book, Rubber Band Engineer. It's full of more awesome and original projects crafted from household hardware. You can find it wherever books are sold.
To truly prank somebody, you have to catch them off-guard. And where are people most susceptible to surprise?...
A small project motor and 9V battery power a pulley belt (rubber band) which is attached to a roll of TP. When pulled on, even slightly, a toggle switch is flicked and the TP rapidly dispenses! This prank requires a bit of investment, but the payoff is supreme!
Update 3/31/12: Wow, 10k views in one day! I didn't think this prank would be popular, but since it is I decided to update step 3 for those of you who actually want to attempt this. Good luck!
4/1/12: Successfully pranked my roommate with this today! This prank was immediately preceded by another great prank. Ah, it was a hilarious moment...
Step 1: Prepare the Prank
- Create a cardboard tube that is slightly smaller in diameter than a TP tube, but bigger than the plastic cylinder that the TP rotates on. I used an empty TP tube and cut out a section, then taped it back together
- Glue or tape a few small strips of cardboard to the tube.
- Insert the tube inside a roll of TP. It should fit easily and snugly.
Step 2: Switch, Motor and Battery
- A project motor that has high torque and low rpm
- A toggle switch that isn't too stiff
- A fresh 9V battery
Step 3: Install and Wait...
- Glue the motor and battery to the TP holder.
- Install the TP roll with insert in the opposite direction that it's intended to unwind. I other words, when the TP spins, it should not unravel because it's spinning the wrong way.
- The switch is the trickiest part, so read carefully: Place a piece of masking tape to the wall and then hot glue the switch onto the tape (this protects the paint). The switch must be positioned in a way that allows the TP to rest gently on the switch while it's off without accidentally triggering the prank. Position the switch carefully and test it before gluing it in place.
- Carefully toggle the switch halfway to the on position just how it's seen in the photo.
- Test it by setting everything up and giving the TP roll a slight tug. If it all works, the TP should rapidly spin (but without unwinding... for now!).
- Tweak it if necessary. Once you're confident it works, turn the TP roll back around, set up the trigger again and wait...
Step 4: Tips for Pranksters Who Actually Want to Do This
- A brand new roll of TP may have too much inertia to unravel quickly, so use a half-used roll for the prank.
- While setting up the motor, make sure the rubberband isn't hooked up to the pulley or you may prematurely set off the prank.
- While setting up the switch, make sure that it is easy to flip, but not so easy that the weight of the TP will eventually trigger it.
- Consider painting all of the components the same color as the wall. The TP dispenser in the bathroom depicted in the video can easily hide everything since it's low to the ground and under a sink, but not all dispensers will hide your prank so easily. Be creative!
- Test it thoroughly. This prank is by no means foolproof.
Here's the links to the components I used:
6-12V Project motor
9V battery lead
Happy April Fools Day!