DIY Bottle Cap Flashlight




Introduction: DIY Bottle Cap Flashlight

About: Making is my passion!

Yes this is a flashlight built in a bottle cap :)

I thought that would be funny to turn a regular cap into a flashlight nothing more only that can I do it?

And yes I made it that was a long journey with a lot of attempts!

But If you stay with me you can make your own ;)

So let's start...

Step 1: Watch the Video First

If the embed link not works just click HERE

Step 2: #1

I don't want to mystify this step just cut off a cap from a bottle with anything you are familier with. (knife, saw, scissors, etc.)

After you cut off the cap sand it flat with sandpaper or a file.

Step 3: #2

Let's working on the top.

Take a small screwdriver, clip or anything and make two tiny holes next to each other in the middle of the cap.

Step 4: #3

Mark each part of the cap at the same spot with a sharpie. That would be a important in the upcoming steps.

Step 5: #4

Take a plastic card and draw around the cap on it.

Take a scissors and cut it out.

It's not necessary to be accurate it's better to make it a little bit bigger than the bottom of the cap ;)

Step 6: #5

Take apart the cap and put away the top. You need just the bottom for this step.

Get a hot glue gun and put a some glue to the bottom of the cap.

Whet it's done put on the plastic disk and push them together so strongly.

Put it down and wait until it completely cooled.

Step 7: #6

While the bottom cools let's working on the top part.

I bought a pack of white LED diodes on ebay. (ebay link)

Insert it into the two small holes on top but leave some space between the cap and diode.

Take your glue gun and put some glue under the LED and push it down to the cap.

Wait until it completely cools down.

Step 8: #7

I needed something which connects the battery with the diode.

This soft copper worked me the best and it came from a picture hanger.

I cut a thin piece of it and bent it to a shape what fit in the cap. See the shape on the pictures.

Step 9: #8

Hot glue gun again!

Put some glue to the inside of the cap pointed from the center to the sharpie sign.

Push the copper into the glue. When it cools down glue the other side of the copper to the side of the cap and push it with a small screwdriver.

Step 10: #9

I used a 3V button cell for energy source. Any 3V battery can be good for this because the this kind of LED's input voltage is nearly 3V. I chose this because this cell's diameter fits well in a cap!

Step 11: #10

Continue with the top.

Use a utility knife and cut off a little piece from the plastic at the sharpie mark. (or nearly at the mark :))

Step 12: #11

Bend the longer leg of the diode into the cutted channel on the plastic cap. Use something hard and thin it's make this step mush more easier. Fix it with some glue.

Step 13: #12

Final step!

Take a plier and roll the other leg of the diode as you can see on the picture.

That will be the other connection to the top of the battery cell.

Step 14: The End

Put together the two parts and close it like you close your soda ;)

So that's simple is this :)

Okay okay it does not sound easy but after some practise it will be a really quick diy project.

You can change the button cell easily as well.

I'm not a professional that was the first time ever I touch LED diodes so If I could make this you can make this as well.

If you have any suggestion to make this easier please let me know in the comment section. I want to continue working with LEDs so every tip can help me be better and better!

I hope you liked this project and if you make one of these please send me a picture I would be very happy for that!

Thanks and see you in an upcomig project.


Step 15: Don't Forget to Check Out the Video Please

As always thanks for your support!

5 People Made This Project!


  • Metalworking Contest

    Metalworking Contest
  • Fix It! Contest

    Fix It! Contest
  • Tiny Home Contest

    Tiny Home Contest

40 Discussions

The 4th graders I work with wanted to make flashlights with me next week and I wanted something that needed limited supplies to keep the cost down but wasn't as basic as taping an LED to a coin battery. This is perfect! Thanks! I'll post the images when we make it.

Very Nice ! !

I was trying something like this with the full bottle and used LED's salvaged from Christmas tree lights. I wanted to make the whole light from salvage parts. The Christmas lights were a great source for LEDs, but I never got the switch right and ended up having to buy switches. This is a fantastic idea for a switch.

1 reply

Cool!.. Great basic idea for other projects start up!!. If a resistor is soldered the battery's life could be extended?? say 2Kohm??

5 replies

it could but the resistor could also eat up what little it saves. an led uses so little power anyway so it would last pretty long especially on a cr2025. in other words it's not worth it unless you have the resistors on hand; you could do a little project to ssee which lasts longer, with or without a resistor, it would be interesting to see

Thank you!! how much a battery like this will last? I know there are super bright LEDs (those usually transparent) and those used for indication and less bright!!. I think this DIY also would work well with concave end head LEDS. This will help to the light dispersion right??


i usually use cr2032 batteries because i can get a lot of them for really cheap (5 for $1 USD) i havent timed one to see how long it will last exactly though. you may not want the concave leds, if the light is dispersed everywhere, it wont be as bright in the direction you're looking. the standard led will shine brighter in front but still some out the sides and it can reflect a bit off what you're pointing it at too. unless you want to put it in a candle holder or set it down to light a tent maybe

a 2Kohm resistor would rather be used with a 12V battery, but that's to limit the current going in. a better use for resistors would for a different coloured LEDs for colours ranging from IR to green (in rainbow sequence), as the forward voltage for them is 1.5-2.2V. so in that case a 0.25W 80 Ohm resistor can be used

If you have an LED and don't know what the proper voltage is, just put a rheostat - a variable resistor - into the circuit with the LED and the battery. Adjust the rheostat until the LED lights up, then measure the voltage across the LED. If you have to use too powerful a battery, inserting a fixed resistor

into the circuit will drop the voltage across the LED to the right level.


These would be pretty cool as an alternative to those small tealight candles. Fun little project, well done!

1 reply

Thank you I will figure out how to make the flames out of something transparent ;)


Not much in this case. Sorry.

No because the power not used by the LED will be lost in the resistor.

Resistors resist current/voltage by heating. Not much in the case, but still.

Make sure you are putting the correct legs of the LED to the correct side of the battery. The longer is positive, the shorter is negative. If you put them the wrong way you will blow the bulb.

5 replies

the only way to blow them up, is to exceed the breakdown voltage, and to do that you'd need something like 5V in forward bias (I've tested LEDs on a 9V battery before, and the way they blow up varies), while a higher voltage of 7V is needed in reverse bias (but depending on the current source, an LED could got up to 185V in reverse)

Not really.. LED's are diodes, and will only create light with power flowing 1-way. the other, will just act like a open circuit because the Diode properties will not allow the voltage to flow. Feeding it >5V without any limiting (resistor) in forward bias (Correct direction) WILL vaporize the GaAS chip. (insert loud POP sound!)

I have a little bug flashlight on my keychain that is nothing more than a 3v battery stuck between the legs of an LED. If I reverse the polarity, nothing happens. I reverse it back and the light works.

Nice i'bble. If you want to learn the basics of LEDs this will do it.

Nothing will happen if you plug it the opposite way, LED's are diodes, Nothing will happen