Introduction: Rapid TP Dispenser Prank

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

The first step is to prepare the cardboard insert. This will allow a motor to turn the TP roll.
  1. 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
  2. Glue or tape a few small strips of cardboard to the tube.
  3. Insert the tube inside a roll of TP. It should fit easily and snugly.

Step 2: Switch, Motor and Battery

Make a simple circuit with a motor, toggle switch, and battery. Just make sure to use...
  1. A project motor that has high torque and low rpm
  2. A toggle switch that isn't too stiff
  3. A fresh 9V battery
No soldering required :)

Step 3: Install and Wait...

Installing the prank may take a few minutes, so this is something that should be done while the mark is out of earshot.
  1. Glue the motor and battery to the TP holder.
  2. 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.
  3. 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.
  4. Carefully toggle the switch halfway to the on position just how it's seen in the photo.
  5. 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!).
  6. Tweak it if necessary. Once you're confident it works, turn the TP roll back around, set up the trigger again and wait...
Testing the trigger...
 

Step 4: Tips for Pranksters Who Actually Want to Do This

This prank is designed to entertain the casual browser at Instructables. If you're actually crazy enough to go to such great lengths to execute this prank, then here's some more advice:
  1. A brand new roll of TP may have too much inertia to unravel quickly, so use a half-used roll for the prank.
  2. While setting up the motor, make sure the rubberband isn't hooked up to the pulley or you may prematurely set off the prank.
  3. 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.
  4. 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!
  5. Test it thoroughly. This prank is by no means foolproof.

Here's the links to the components I used:

Toggle switch
6-12V Project motor
9V battery lead
Pulley
Rubberbands

Happy April Fools Day!

Comments

author
chemkid42 (author)2012-04-03

to do this to the staff only bathrooms at a public high school would be priceless

author
qwerty987 (author)2012-04-01

i just now put this into my parents bathroom with a pressure switch under the seat and the wires hidden as best as i can. Now all i have to do is wait for it. One other prank i did is plug in my wireless mouse to my parents computer and pretend to be using it on my computer.

author
LanceMakes (author)qwerty9872012-04-02

Ah a pressure switch under the seat is a much more elegant trigger. good thinking

author
astrong0 (author)2012-04-01

awesome 'ible! nice vid too, did anyone else watch the drunk guy sing bohemian rhapsody? it caught my attention.

author
Ben Nguyen (author)2012-04-01

Great idea! Now, you cold also try reversing the motor to cause the roll to spew out an uncontrollable stream of toilet paper (although it would most likely cost you a roll of paper).

Keep it up!

author
josephlebold (author)Ben Nguyen2012-04-01

Yeah really... Did you happen to watch the video?

author
Ben Nguyen (author)josephlebold2012-04-01

Ahh, my bad. I only watched the one where it went backwards and rolled itself up. Thanks for pointing that out.

author
old_code (author)2012-04-01

Or April Fool's Day, if you prefer that version of the day. (more caffeine, please.)

author
old_code (author)2012-04-01

What a thought for April's Fool Day!

Wonderful!

author
jetpower (author)2012-04-01

Hi-larious! Suggested mod: Design a circuit to roll it out a few feet and then reverse the motor to snap it back.

author
DGerman (author)2012-04-01

you so NEED one of these!!

author
pcgirl (author)2012-04-01

Wish I'd seen this earlier! Excellent.. will save it for next year. Mwaa ha ha ha

author
Jakwiebus (author)2012-03-31

this is SOOO going in my parents house tomorrow =D

author
Robot Lover (author)2012-03-29

Could we get a video of it dispensing all of the toilet paper? This is a funny prank!

author
Jayefuu (author)2012-03-28

Brilliant prank, good work!

author
mikeasaurus (author)2012-03-28

You're not using the washrooms here the next time you visit the lab.

author
Jayefuu (author)mikeasaurus2012-03-28

+1

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Bio: I'm a writer, maker, and educator. For free lesson plans and teaching materials, check out LanceMakes.com.
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