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
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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Kirbsome!5 years ago

Throwies on steroids -

7 LEDs arranged in a ring
LED Ultrie.jpg

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 :)

so simple yet so powerful

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.

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: http://flickr.com/photos/everythingdigital/sets/72057594069888500/

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.
Q-Branch (author)  everythingdigital9 years ago
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!

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

How long do they last?

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

not sure city officials would be that impressed.

fun with LED throwies
wikd4 days ago

Thank you for //////

Awesome LED Collections I really love it



wanna try it

I really impressed
after read this because of some quality work and informative thoughts . I
just wanna say thanks for the writer and wish you all the best for coming !.
AllW9 days ago

Excellent article.
Very interesting to read. I really love to read such a nice article. Thanks!
keep rocking.


AllW9 days ago

Excellent article.
Very interesting to read. I really love to read such a nice article. Thanks!
keep rocking.


oalvarez211 days ago

how long they last?

Awesome LED Collections I love it



I fit the definition of Sigma perfectly, with the minor exception of not being very Alpha.


TanyaT215 days ago

Amazing Led Throwies! I love it!

Thanks to author.

ShortedOut19 days ago

LED throwies are a cool idea ... in the right setting. Both button cell batteries and neodymium magnets are harmful if swallowed by wildlife (birds, etc.), pets or children. Button cells will eat through the stomach within two hours, causing massive bacterial infection. So have fun, but do so responsibly.

coventrymakerspace made it!22 days ago

We made this for our community event. We had to change it a bit for safety. It was awesome! Thanks!


elliotnash1 month ago

This looks really cool. Guess I now know what I'll be doing before Christmas comes.

Shirleydavis2 months ago


KIRAN PALK2 months ago

sir, its a really nice concept ..................... but i have one doubt ......that is

we require different batteries and magnet for each led?

elliotnash2 months ago

Looks really cool. I guess I should start preparing early for Chrismas now when I know of this awesome tutorial. :D

T0BY2 months ago
Absolutely brilliant!
WaqarH12 months ago

Thanks for your help. I was looking for a good blog where i can learn how to make a working LED throwie. I think it is one of the most useful websites on this topic.

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WaqarH12 months ago

It is the best webiste about led throwies. I have seen many websites but this website has shared ideas that i haven't found on any other webiste.


thermallyme3 months ago

Cool project!

Harrys63 months ago

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Harrys63 months ago

i want to say that your post is really nice i appreciate your work , Keep it up
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GwyneddS3 months ago

I made one for my hair! It won't last long because it's so many LEDs, but it's fun for now. Just used electrical tape and a paperclip.

thowie clippy 2.jpgthrowie clippy.jpg
Harrys64 months ago

you so much for sharing this type of wonderful post. I really appreciate your
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HelenR6 months ago

I don't want to be a party-pooper, but those lithium batteries are lethal to children. So you might want to think carefully about where you put these things.

Conor M HelenR4 months ago

Hopefully there mums/dads are good parents and wont let them eat them

Snellingkorey7 months ago

My dog would love this, can you make it dog proof?

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