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.
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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.

Neodym1 year ago

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


makerboy1125 years ago
You can buy ten rare earth magnets at Harbor Freight for 2 bucks
llamma10105 years ago
umm i think you should update the price on the epoxy it now costs 59.97!!!!!!!!!!!!!!!!!
 The led's are about $0.16, but you have to order $25 worth!

$25/0.16= 156.25 (Rounded to 157) LEDs!

I don't need 157 LED throwies.
jhames6 years ago
For someone that would prefer not to shop online what electronic stores carry LEDs? Lives in the US.
radio shack would be the best. and it was the best in canada til they closed every canadian store
What are these "rare earth magnet" things? I've seen them onmany projects, nut how do they differ from magnets, let's say, from aMagnetix toy. (I don't mean to sound rude, I'm just curious.)
 they are made from neyodinium(?) and are extremely strong.
Okay, thanks.
so when it says its a 1.8v - 2.4v LED will it still work with a 3v battery or what? Will it just burnout faster?

and of http://www.kjmagnetics.com/products.asp?cat=17 or http://www.gaussboys.com/magnets/discs/ which magnet is best? a 10mm by 2mm?
That voltage rating is for the LED itself. Basically, when it is turned on, there will be 1.8-2.4V across it. So, you need at least 2.4V for the LED to turn on (preferably a little more).

However, you usually don't want to have just an LED and a battery. You want to have a resistor in front of it, too (It's OK in this case because you're using a 3V battery with a 3V diode, so it's pretty close).

In your case, I would put a 30 Ohm resistor in series with the diode. The diode will drop 2.4V and the resistor will drop the other 0.6V. The resistor will cause about 20mA of current to flow through the diode, which should be enough to turn it on!
So are the magnets necessary if I'm just wanting to add LEDs to a costume (I'm new to this...so the lights will glow, without the magnet?)
REA7 years ago
the magnets are alot cheaper herehere
xfnord REA6 years ago
Thats more expensive the the price for a complete led throwie. check this out[]
REA xfnord6 years ago
>Jun 20, 2008.

it was cheeper a year ago when i posted...
Geo242 REA6 years ago
The link you posted now shows magnets between $.50 and $.60 each for orders less than 100, but it may have been cheaper when you posted it.
REA Geo2426 years ago
oh wow! it was about $0.19 per magnet when i had posted that.
laurajean006 years ago
also wondering if anyone could guess at how many throwies i would need to put in a lantern for an outdoor wedding reception?
how big is the lantern? a clever idea would be to buy a lantern that has the same effect as a frosted window, transfer a small light source over that large area, for a good lamp, i would say 15-30, depening on how you make the throwies
Gasburner6 years ago
laurajean006 years ago
can i use 5mm LEDs instead of 10mm? whats the difference?
cartufer9 years ago
i've been finding stuff a lot cheaper than this, packs of 100 leds for $2, lithiums for $.20, $5 per 100 neodymium magnets, cost estimated at 36 cents each
where bro????
Geo242 purty7076 years ago
Here is what I found, and I have ordered many times from this site and they are great.

Magnets for $13.50 per 100 - http://www.dealextreme.com/details.dx/sku.13513

Batteries for $3.47 per 20 - http://www.dealextreme.com/details.dx/sku.831 OR http://www.dealextreme.com/details.dx/sku.751 (for $3.66)

LEDs (5mm not 10mm) for $0.07 each - http://www.newark.com/spc-technology/mc20455/led-lamp/dp/87K7081

Total cost = ~ $.38 each

Newark has a huge selection and great prices from my experience, but 10mm LEDs seem quite a bit more expensive and not that much more light. The link above points to ones with 100 degree viewing angle. Keep the viewing angle in mind when purchasing any LEDs.
[no offense but] i deem this comment useless without further information!!
yes cartufer9 years ago
where have you found this stuff for cheaper? thanks
Sullen70 yes8 years ago
I got magnets at 14 cents each (100 minimum order) at https://www.magnet4sale.com/xcart4/product.php?productid=16260&cat=295&page=3
cartufer yes9 years ago
the magnets you link to are 533 cubic millimeters, the magnets these guys are using are about 5054 cubic millimeters, so there's actually almost ten times the amount of magnet there. use the cheap ones and tell us how well they stick, though .

also, I assume they use 10mm diffused LEDs since they are brighter and can be seen from a wider angle.
the LED's at the site you gave are different than the ones it says to use. Have you tried making them with your LED's? Does it work as good?
It'll be bad when people green clusters of these on street lights, or are those plastic...I can't remember.
T-MAC25126 years ago
can you make them without a magnet
the magnet is so you can stick them to stuff, so yes you can.
dcmania216 years ago
I bought a pack of LEDs from radioshack, and the leds are not bright enogh, does anybody know why?
jav6 years ago
magnetic LEDs are available at thinkgeek.com. package of 20 = $9.99 Fab for holiday lights on the car! Plus cheaper than making them!
saxophones6 years ago
where do you get LED lights
At all Electronics Corp in California they have the same led's at Ten for a buck now if your at the website you have to pay shipping!
codongolev6 years ago
if you've got an old magnetix set (the magnetic sticks with ball bearings, a sort of kiddie building toy) you can hit it with a hammer, and the magnets pop right out. they're not necessarily super- strong, but they're stronger than your regular magnets.
zoned-out6 years ago
The Ni-Cu-Ni plated magnets are pretty spendy for just a few. Do the magnets HAVE to be Ni-Cu-Ni plated??? or can they be nickle plated?
I found Rare-Earth Neodymium-Iron-Boron (NdFeB) magnets that are nickle plated and come in large packs for 9.00$ here
Are these yay or nay for the use in LED throwies?
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