Quick Easy Waterproof Flashlight Using an Inner Tube




About: Oh wow a lot can change in three years. can't say I forgot about this place but got pushed away from it a little.

Electricity and water are never a good thing to mix, but you never want to be caught out in the dark without a flashlight. Whether you're just a hiker and worried about rain, or prefer to canoe or kayak and are constantly worried about ending up in the drink, a waterproof flashlight is just as cheap and easy to make, as it is to buy.

Disclaimer: Water and electricity are a bad combination. It can short out your equipment, and depending on what it is it can give you a decent jolt. While I have made and tested this flashlight take everything said with a grain of salt and some common sense. Always be careful when putting dangerous elements together.

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Step 1: What You Need

A few things to consider. Stay away from self sealing tires. They are lined with a slime that is forced into punctures where it will harden. Needless to say, that would become a horrific mess if you try to cut it. If you don't have any tubes with holes in them you could always consider upgrading and then having the old inner tubes to play with, and if you do have a tube with a hole then you of course want to use a section that isn't pierced for this project.

Flash Light
Inner tube from a bicycle
needle and thread
clear plastic bag
super glue

Utility knife or scissors

Step 2: Measure Twice, Cut Twice

Any kind of flashlight will do. One that is slimmer will be easier to fit the rubber around, but depending on the type of inner tube, and how well used it is, the rubber will be willing to stretch. Just measure your flashlight, and then measure out a length of tubing about an inch and a half or two inches longer. After that just cut the tube to length.

Step 3: Sealing the Back End

Because batteries and water never play nice, this flashlight will need to be sealed up tight. Take the extra inch and a half or so of material on the back end, and glue the insides together. Go ahead and clamp it, wiping up any excess. Airtight is watertight, so if one end is shut, there is less to worry about. After the glue has set, just for some extra insurance I stitched around the edge, staying within the glued area, with a double layer on the inside edge by the flashlight.

Now this could easily be shortened, but I added the extra on so that I could cut a loop for a lanyard or clip. 

Step 4: Putting Things Together

Now we can go ahead and slide the flashlight into the tube. Depending on how big your flashlight is, it can be a good fit, or a little snug, either is okay. For me, the body slid in without much difficulty, although I did have to roll a collar, and then unroll it over the head of the flashlight.

One step I did forget to photograph, and it should be done no later than covering the head of the flashlight. Take the plastic bag, I used a plain sandwich bag, and cut out a small corner. unscrew the head of the flashlight and cover the bulb and the tip with the plastic bag. It should extend past the threading for the head, as when you screw it back on, that will provide extra insulation for the electronics against the elements.

Step 5: Finishing Up

Once you have the bulb covered with the plastic, and the head screwed back on, unroll the collar, rolling it up over the head. Trim any excess that obscures the beam, and you should have a waterproof flashlight thats willing to go anywhere you take it.

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    26 Discussions


    8 years ago on Step 2

    Seems like you'd need a flashlight with a button toggle rather than a switch or twist style on/off mechanism.

    1 reply

    Reply 8 years ago on Step 2

    Very true. Something I hadn't mentioned because I did have the push button design myself. To note, though: having this design, there is some flexibility in the tubing. It would be my assumption that it may not affect a slide switch, or even a twist. I have managed to adjust the focus of the beam by twisting the cap while it is in the sleeve.

    There is a thin piece of plastic, like a ziploc bag, that is inside the head of the flashlight, covered in step 5. It covers the bulb and actually passes back to the threads where the head screws on. With the head screwed on it seals itself. It may leak in from the front of the lens, but no water gets into the wiring.

    I actually would've preferred the plastic to be external, but I ran into some difficulty with keeping it on, and pulling the rubber over it, so I adapted slightly. I'll try to get around to taking the pictures for that part.

    I didn't try welding, because the only decent tool I'd have for that is a soldering iron, and I'd be afraid of not getting a consistent seal throughout. Maybe with a hot air gun that would work. You'd just want to make sure its uniform throughout.


    Reply 8 years ago on Introduction

    Nope. You can weld metal, plastic, rubber, all sorts of things. Pretty much anything that melts(chocolate!).


    Reply 8 years ago on Introduction

    I think when he said welding he meant melting the rubber together compared to gluing it. Not anything with welding the flashlight. So it is a good idea if you have the tools to do it right.


    Reply 8 years ago on Introduction

    if it could be charged while sealed by induction . That might be cool . The gas produced by batteries should be taken into account also in a 100% sealed app . maybe a 1 way valve ?


    8 years ago on Step 3

    could you use a hole punch (like the ones you use to file papers to make the hole? a more perfectly round hole will handle stresses better (as well as being one less step for playing with knives), and be less likely to tear. it's been years since i last played with an inner tube, so i'm not sure if the rubber will be too thick for this?

    1 reply

    Reply 8 years ago on Introduction

    I think it would be more of a matter of can you get the punch around it. The rubber seemed to cut pretty readily with scissors and the like so that shouldn't be a problem.


    8 years ago on Introduction

    This is a nice trade off between a permanent solution like filling the flashlight with mineral oil (As seen HERE) and the ultra-quick solution that I used to use which was a non-lubricated condom with the end tied in a knot.