Developed by the Graffiti Research Lab a division of the Eyebeam R&D OpenLab, LED Throwies are an inexpensive way to add color to any ferromagnetic surface in your neighborhood. A Throwie consists of a lithium battery, a 10mm diffused LED and a rare-earth magnet taped together. Throw it up high and in quantity to impress your friends and city officials.

Click on this link to see the LED Throwies in action in NYC thanks to resitor and fi5e!
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Step 1: Materials List

Picture of Materials List
LED throwies consist of only a few inexpensive parts and can be made for ~$1.00 per Throwie. You can reference the parts list below or download the attached spreadsheet for more info on parts, part's numbers, vendors and application notes.

Part: 10mm Diffused LED
Vendor: HB Electronic Components
Average cost: $0.20 avg per LED
Notes: Cost reductions for larger quantities. Comes in red, blue, amber, white in both diffused and clear. Diffused works better than water clear for the Throwie application. HB has even created a Throwies packs page with deals on 10mm LEDs and lithium batteries!

Part: CR2032 3V Lithium Batteries
Vendor: CheapBatteries.com
Cost: $0.25 per battery
Notes: Cost reductions for larger quantities. With the 2032 Lithium batter, depending on the weather and the LED color, your Throwie should last around 1 -2 weeks.

Part: 1-inch wide Strapping Tape
Vendor: Your local hardware store
Cost: $2.00 for one roll
Notes: One roll will make many throwies

Part: 1/2" Dia x 1/8" Thick NdFeB Disc Magnet, Ni-Cu-Ni plated
Vendor:Amazing Magnets
Cost: $13.00 per 25 magnets
Notes: Cost reductions for larger quantities

Part: Conductive Epoxy
Vendor: Newark In One
Cost: $32.00
Notes: The epoxy is optional.

Step 2: Test the LED

Picture of Test the LED
Test your LED to determine color, brightness and functionality. Pinch the LED legs, or leads, to the battery terminals. The longer LED lead, called the anode, should be touching the positive terminal (+) of the battery and the shorter LED lead, called the cathode, should be touching the negative terminal (-) of the battery.

Note that the positive terminal on the battery has a larger contact surface than the negative terminal. The positive terminal extends around the sides of the battery. Don't let the cathode lead of the LED accidentally touch the positive terminal of the battery. This will create a short and cause the LED to function improperly.

For more information on LEDs click here.
For more information on batteries click here.

Step 3: Tape the LED to the battery

Picture of Tape the LED to the battery
Cut off a piece of 1-inch wide strapping tape approximately 7-inches long. Tape the LED leads to the battery by wrapping tape 2-3 times around both sides of the battery. Keep the tape very tight as you wrap.

The LED should not be flickering.

Step 4: Tape the magnet to the battery

Picture of Tape the magnet to the battery
Now, place the magnet on the positive terminal of the battery and continue to tightly wrap the tape. The magnet should be held firmly to the battery.

If the magnet is stuck to a ferromagnetic surface, dont pull on the LED throwie. Apply a lateral force to the magnet and slide it off the surface while lifting it with a fingernail or tool.

Remember to keep the magnet away from conventional hardrives, credit cards and other data storage devices.

Step 5: Toss your Throwie

Picture of Toss your Throwie
The LED throwie is ready to be tossed onto a ferromagnetic surface. Practice tossing your throwies. Work on your accuracy and your own personal technique. Every throwie wont stick every time, but if you toss them gently, they will stick eventually. Get them up high and in large quantities for greatest enjoyment.

Step 6: Plan a campaign

Picture of Plan a campaign
Now, find a building or structure that will attract the magnets, form a crew, wait until night, and get some throwies up. If you do it around a crowd of people, they will probably try to get into the act. It can quickly dissend into chaotic fun. Give a hand-full of throwies to a stranger and let them get up too. Remember, Throwies are only a temporary alteration of your local environment. Depending on the color, Throwies can last upto two weeks, but you arent going to cause any permanent damage, so most property owners wont mind. And The NYPD loves throwies!

Click on this link to see the LED Throwies in action!

Step 7: Other applications and upgrades

Picture of Other applications and upgrades
Other applications:

Other than tossing it, you can also use your LED throwie to write in the air with light while taking a long exposure flick. You can put them on your bike as an additional reflector. You can put the on surveillance cameras to make them more visible at night. You can use them to play a version of bocci ball on a magnetic surface in the dark.


You can make a better LED throwie by using shrink tubing on each lead to make sure they don't short to each other or the battery. This upgrade will allow you to bend the LED so it faces in the direction you choose. You can also dip the throwie in epoxy, silicon or potting compound to make an all-weather LED Throwie. A resistor in series would allow you to increase the throwie shelf-life. Bigger batteries = longer life. Stronger magnets = increased stick probability. You could add a solar panel, photocell, etc...Have fun.

User Upgrades:

Flickr instructional set for thowie on/off switch mod -- by A. Joyce, aka. EverythingDigital
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how long will the batteries last?

davidbarcomb8 months ago

Very nice project and well explained tutorial. Thanks

StumpChunkman8 months ago

I've loved and used this tutorial for years. I hope you don't mind, but a friend and I wanted to make a song that centered around a tutorial, and this seemed like an ideal candidate. Thank you so much!


TheGeek198410 months ago
Ah...LED Throwies...I remember, way before I signed up with Instructables, I was bored and surfing the internet, and I stumbled upon an article that had the main picture from this 'ible, and all the fun things you could throw them at and make them stick. Then there was a link, so I clicked it. Best. Decision. Ever. This was the first instructable I ever read, and the first I ever built. I would throw them at my front door and use the square patterns as sort of targets, like a game.

What was the first instructable you read/followed?
RobertGoldring11 months ago

excellent idea, you could really make a statement at Christmas with these.

TfhRober11 months ago

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Thats sweet

Jan_Henrik1 year ago

Very cool i like it!!! :)

Its amazing

mousepaper1 year ago

Thats superb

mousepaper1 year ago

Extremely good

Its tremendous :)




fastbobble1 year ago

Its spectacular :)

gorgeddamp1 year ago

Thats wonderful...

This is awesome!

illrings1 year ago

Its splendid :)

airbugger1 year ago


Or you may order magnets from www.hobber.ro

It has over 230 neodymium and ferrite magnets

Thats one awesome

Neodym1 year ago

and if you'd like to get the best price:


headlymph1 year ago


tealrink1 year ago


Thats nice


harechubby1 year ago




ritchie561 year ago

May I make a suggestion. LEDs by definition do not regulate the current passing through them. In other words, if you don't limit the current passing through them with a series resistor, then they will allow as much current to flow through them as the battery can deliver. The LEDs you mention have a maximum current limit of 25mA (0.025A). The button batteries can delivery 10x that much current in a short period. The result will be a very shortened LED life and a burned out battery. Red LEDs drop about 2 volts and the battery can deliver 3 volts, so a 50-ohm series resistor is in order (for a safe 20mA current flow). The blue and green LEDs need 3-3.6 volts to operate and would require 2 batteries stacked together to produce 6 volts. For blues and greens I would use a 130-ohm series resistor. By doing this, the LEDs will illuminate much longer. The resistor can be put on the positive or negative side of the battery between the battery and one of the LED leads.

calmlunch1 year ago


calmlunch1 year ago


clapfilk1 year ago


clapfilk1 year ago





clickyummy1 year ago


clickyummy1 year ago


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