Introduction: LED Throwies

Picture of LED Throwies

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!

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
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


everythingdigital (author)2006-02-25

I have posted a how-to on making throwies with removable tabs where you can pull it out to turn the LED on and slide it back in to turn it bad off. It's not very hard to implement, and is quite useful for conserving battery power.

Here's the link:

I'm also working on throwies that automatically turn on upon sticking to something and off when they are removed (as suggested above), and I have a few prototypes working but there are still some bugs to work out.

I have included your how-to on the G.R.L. Throwies site and in the upgrade section of the throwies instructables post. Thanks so much for the mods and looking forward to the next rev!

JulieHenriksen (author)Q-Branch2014-08-21

Best quote: "Throw it up high and in quantity to impress your friends and city officials."

How long do they last?

njreyn (author)JulieHenriksen2015-04-30

Unknowable. Friends can be fickle, and city officials often disappear once installed.

VegaNadir (author)njreyn2015-10-28


not sure city officials would be that impressed.

Kirbsome! (author)2009-11-26


Throwies on steroids -

7 LEDs arranged in a ring

adame_jh (author)Kirbsome!2015-05-17

Hello! Do you have an instructable for this one? I want to apply something similar for a soft toy I'm making, just took my first steps on LED 'wiring' yesterday and your solution seems to fit what I had in mind... without entering into Arduino land _I'm not ready yet! Thank you :)

Akin Yildiz (author)Kirbsome!2014-04-20

so simple yet so powerful

frenzy (author)Kirbsome!2010-06-14

I have great news, you are today's winner of the "I Made It" Challenge for the month of june. Thank you so much for being a part of the instructables community and encouraging authors to post more projects!

For winning you are receiving a 3 month pro-membership.

sensoryhouse (author)2007-10-15

fun with LED throwies

brick connoisseur (author)2018-01-19

this is a great project to do when bored because it is fun, and inexpensive

sergioa3w (author)2017-12-06

A very fun idea to make and apply. I love the simplicity of something so beautiful. This Christmas my house will be a party of light and color.

Thank you very much for sharing.

EmK6 (author)2017-08-10

This is a very fun and intriguing instructable that requires a good amount of responsibility. These Throwies would be perfect for parties.

BastidgeC (author)2017-07-07

Throwing hazardous batteries around shouldn't be promoted. This instructable is awful.

GreenMoon (author)2017-07-06

If a dog, or any animal (or child), ingested just 2 of the magnets, they could die. Magnets in the digestive system are amazingly dangerous.

Also, lithium (or any batteries) should be disposed of responsibly (recycling/hazardous waste center). Please don't throw electronic components into the environment. Plus, it's rude to ask others to clean up your pollution.

kiel814 (author)2017-07-06

This old instructable was featured in today's email. I realize it is really old, but I was really annoyed by it. It is actually promoting the contamination of the environment, plus unauthorized modification of public/private property.

I realize throwing illuminated, magnetic toys around can be fun, but this should actually be done in your own property, not in public areas or other peoples homes without their permission. People are likely to be very annoyed by the fact that they have to clean up someone else's mess, specially considering that throwies can reach locations that could be difficult or even dangerous to access.

It should also contain advise about how to dispose of batteries safely or at least a warning about environmental effects.

I encourage people to flag this as inappropriate, in the hopes it is either modified of removed.

GreenMoon (author)kiel8142017-07-06

I agree. It is irresponsible to throw hazardous materials into the environment. And what a waste.

devicemodder (author)2017-06-13

haven't made a throwie in years... gotta make more.

Schuyler (author)2015-12-24

This remains a phenomenally bad idea. Instructables should have nothing to do with promoting it, and neither should anyone else. Aside from the glib, "impress . . . your city officials," which actually means something(i.e., demands allocations of resources, your tax dollars, to clean up someone else's mess, i.e., yours), it has "pollution" written all over. Tossing lithium batteries into the environment wildly-nilly, along with the rest of the ingredients of a "Throwy,"(it sounds so fun!) is the height of irresponsibility, the companies selling parts specifically for such should be sanctioned as well. I'm not opposed to childish behavior, which this is(it is not "art" on any level). But if you must, go throw toilet paper rolls over your friends' trees, or some such thing. Lithium-ion batteries are classified as "hazardous waste," whether in your phone, portable drill, Tesla, or "Throwy," and should be disposed of properly, without exception. I haven't even touched on the pollution associated with rare-earth magnets. Educate yourself, people! And grow up! Please! We can't go on like this forever.

DeliriousSyntax (author)Schuyler2016-01-29

Why don't you go ahead and explain the harm in this. inform me

well, he allready gave all information you need to determine the harm it does. for more information see my latest answer on your trolling comment (above)

(I know I risk feeding a troll here, but for the sake of clarification…)

Not trolling I just really don't see the harm and want to know.

either you're enormously lazy, live in a place where they block google – or I shall remain regarding you a troll. I'll make that my very last ration, as not to overfeed you:

as I allready stated, Schulyer gave you most information you need to thoroughly educate yourself on that topic. I added some and will leave you on your own with that.

so now my little troll, run free!

joskdie (author)lukas.hofmann2017-05-31

you made the assertion, you provide the evidence. Right now you are passing the burden of evidence which logically means you don't have a defendable argument and just want to make noise and make yourself feel special.

lukas.hofmann (author)joskdie2017-05-31

evidence for what exactely? if it's about lithium being a part of button cells or these lithium compounds being harmful for the environement — I think you can still google that yourself.
"making myself feel special" — well. at least I don't need to throw illuminated hazardous waste on the streets fot that.

Still not a troll was just wondering and thanks kinda even though you still call me a troll. I'm just interested enough to ask questions about not interested enough on the topic to go do research on it.

djoghurt (author)Schuyler2016-01-16

better said than i could have.

jhhweber (author)Schuyler2016-01-15

Get off your cross we need the wood.

Schuyler (author)jhhweber2016-01-15

Funny. Answer the question please.

xharass_natox (author)2017-05-26

Would these LEDs work with the suggested cr2032 battery?

"5mm LEDs Wave Length:460 - 470 nm. Viewing Angle : 20 ~ 25 Degree. Max 20mA. 15000mcd. Forward Voltage (V) : 3.2 ~ 3.5. Reverse Current (uA) : <=10."

Peterthinking (author)2017-05-20

How about a solar cell and a capacitor instead of a battery? Comes on every night like a BEAM robot.

undanganpernikahan (author)2017-01-05

Will be amazing for party... Maybe next NYE.

Sscowman2004 (author)2016-12-16

wow that is cool ;)

T0BY (author)2016-12-06

Thanks for that, very helpful.

RobinH75 (author)2016-11-24

Letting the "wrong" LED lead touch the battery won't cause a short or
damage either component. LEDs are diodes and only function one way
round. It won't harm the LED to be reverse-biased, and indeed it's
designed to be connected this way in larger circuits. Lithium batteries
shouldn't present a disposal hazard when used in this way, as they'll be
fully discharged when they do reach landfill.

Better than chucking them once they've run down, why not "catch" them with a stick/net/string, and re-build them with a new battery?

lukas.hofmann (author)2016-01-24

is this instructable actually promoting the fabrication of "throwies" (as in "throw-away") that consist of an LED and a Lithium Battery?

if so, I would like to line up with Shuyler, ask the author to educate himself concerning the ecological and social aspects of his proposal and publishing it on

I also agree that "Instructables should have nothing to do with promoting it, and neither
should anyone else."

Are you serious it's a light bulb and a battery throw it around have a little fun and throw them away... What's the harm?

I have little hope that facts will convince anyone who defends this practise.
but you asked what the harm is and I'll answer:

the harm is the battery

the hazardous ingredients of practically any type of Alkaline battery make it absolutely crucial to mindfully dispose of — not just throw them anywhere.
landfill should NOT be an option for disposal here.
closed substance cycle waste management defenitely is.

besides, throwing that kind of stuff is mere waste of material
(the value of wich unfortunately does not show in its price)
— economically and ecologically speaking.

(the fact that this type of button cell also contains lithium might also be a problem as lithium occures in such a concentration nowhere on this planet — except in man-made batteries.)

((and I would even regard it less of a problem if it WAS an actual light bulb, but it isn't. It's a piece of epoxy, sticking to a piece of acrylic, holding a little semiconductor…))

korhankaya (author)lukas.hofmann2016-04-16

Thats +1 Please don't pollute our earth for fun, that is total ignorance !!!

Ok, it's hazardous, but what kind of damage would throwing a few outside do? I probably sound ignorant to you, but I really just want to find out how big of a problem it is in actual numbers and what it will do to environment (I'm guessing the damage it causes is to the environment).

dude, this was posted 10 years ago.

llamb50 (author)2016-03-03

Do you have to use the 10mm Diffused LED lights, or can you use 5mm or 3mm

devicemodder (author)llamb502016-04-15

Any LEDs will work. Just 10mm look the best.

devicemodder (author)2016-04-15

Wow, hard to believe this was posted 10 years ago.

10103 (author)2016-04-01

that is cool

Seosem (author)2016-03-29

It's great!
My nephew has long enjoyed doing it
Thank you very much for sharing. Keep going

wwalker iii (author)2016-03-01

Your LED throwies link video is broken

VegaNadir (author)2015-10-26

I appreciate the very informative article.

I have several 3mm LEDs that would work with the 3V CR2032 batteries. However, I know of some smaller 3V lithium cell batteries and would rather use the tiniest ones possible. I'm going to use them for something I've been working on and want the battery to be as invisible as possible.

If you please, what is the smallest sized battery you know of that would work for these? Also, I wouldn't mind if they were a little dimmer, so ought I to use less than 3V? Thank you very much.

Probably hearing aid batteries.

About This Instructable



Bio: I made weapons for the British government for over thirty-five years. Now that I am retired, I have gotten involved in outfitting graffiti writers and ... More »
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