Introduction: Thermo-flask From Junk

It's a wasteland outside

And your water gets hot...

Well, NOT!

Cause you have a termo-flask!

"Who the heck are you" - you ask...


I'm the one who's bad at haiku, but this is how you can make a thermo-flask out of garbage.


Of materials you'll need:

  • A bunch of plastic bottles (ignore the image abow; during the process I went and made a few twicks along the way, so ypu'll learn about the kinds of plastic bottles, you'll need eventualy as you progress)
  • A flat glass bottle, the kind, you'd usually find some whyskey or vodka in. Mine was 370ml of capasity.
  • Insulation material. I use two kinds which are prectically the same - sheets of foamed polyethylene; may be found in packages of all sorts or as an insulation material for laminated floors.
  • Reflective film or aluminium foil. May be obtained in a form of an emptied bag of potato chips.. or a roll of aluminium foil. Mine was taken from bottles of beer where it served as lables.

Of tools:

  • Heat gun
  • knife
  • scissors
  • random stuff
  • gloves

Step 1:

First of all take your glass bottle of choice and smack a bunch of foil or reflective film over it shiny surface facing inwards.

Allegedly it suppose to reflect either sun rays from outside or radiating heat from inside. Or both.

Leave certain amount of material overhanging over the bottom edge of the bottle but also enough to cover the "shoulders"

Secure with scotch tape if needed.

Step 2:

For the first layer of insulation I'm using a 3mm(ish) sheeth of foamed polyethylene.

Wrap it accurately in one layer and secure with tape.

Step 3:

Then one more layer of reflective film/foil is added facing outwards because I decided so.

Step 4:

To secure the first layer of insulation a specialy prepared sleeve is required. Plane cylindrical 1,25L bottle with round domed top is used here. The neck and the bottom are removed and the lenght of the sleeve is taken to be slightly longer than the glass bottle.

Then the sleeve is slid over the flask assembly.

If you feel restitance the materials express against being slid one against each other like I did - generously smudge everything with baby powder. It really does the trick.

Step 5:

After the sleeve is positioned where it should be positioned, use heat gun to apply heat to the heating elements of the...

Set the heat gun to 200-300C and try to apply heat uniformely toward all surfaces. PET plastic will shrink, and if procedure done thoroughly the resulting surface should come out smooth and uniform.

No need to be worried about axcessive foam trapped between the layers; when heaqted it becomes quite compliant and.. just takes it's place eventually.

Step 6:

If you have troubles with flaps of excessive plastic on the bottom edge, as I did - do what I did, AKA heat the plastic until it's soft and maluable and press it against flat surface to flatten it out. Worked for me.

This accomplishes the first layer of insulation.

Step 7:

While the second layer of insulation can be done in exact same way, just because I happened to have this material, I'm gonna do it wit this material.

Basically it's the same foamed polyethylene but with the reflective layer already adhered to it. It's readilyy available as an insulational metrial so it shouldn't be all that hard to find if you want it.

So the flask gets wrapped in one more layer.

Step 8:

A sleeve similar to the previous one is made once again but at this time out of larger (2L) bottle

Step 9:

Although before shrinking the sleeve over the insulation layer like before we need to mark and cut holes for accomodating the attachements. A bottle lod is used as template and two holes are marked at the shoulders of the bottle facing slightly more toward the back, or concave side.

The third hole is marked in the middle of the top portion of the front portion.

Step 10:

One thing I've learned while dealing the plastic bottles the way I do AKA shrinking over certain shapes by heating, is that it's kind of important that the edges don't contain any snags or sharp cuts into the material because those, whilst shrinking, very likely to broduce starting points for tears.

You want your edges smooth and clean.

Thus having a heated blade, like the one I have, and using it to cut butter smooth holes in plastic bottles is not only kind of important but also goddamn convenient.

Cut smooth holes according to your markings.

Step 11:

When that done, take three bottles with domed tops and cut them tops off with certain amount of excess material.

I used a roll of masking tape to mark more-or-less precise circles around the necks, which are also concentrical to the afformentioned necks. Then the tops were refined to their final shape by trimming the excess material... and positioned within the sleeve with the necks protruding from inside the way it shown.

Step 12:

Then the sleeve is put onto the flask body and, after being carefuly positioned and aligned is shrunk secure into place.

I forgot to take more photos of this stage.

It looks rather nice at this point.

Step 13:

It's kind of out of order but randomly at this point I decided to dress the lid a little bit. Thus a lid out of plastic bottle was heated sufficiently and pressed ove the other lid where it resided ever since staying permanently attached.

Step 14:

I'm not going to describe what's going on here in much if any details cause it's... kind of worked... sort of looks ok...

But I'm not sure, I'll have to vork on this bit a bit more.

But in general you can deduct stuff from pictures I suppose...

Step 15:

Anyway... this is the point where things went a bit dodgu and I wasn't quite sure what the hell I was doing.

In general I tiried to to do the same thing I did with the prototype I'd done earlier. But for whatever reason stuff wasn't quite working: the plastic material behaved kind of wonky and I generaly wan't pleased.

But here's what I did. Out of remaining bodies of the bottles I've cut a bunch of loops and used them to create sort of a lashing around the protruding perts to further secure them in place. This one way to proceed that may be accomplished with only using scissors.

Step 16:

The other way, that... kind of provided more accurate result and definitely one, more comfortable to proceed with is to cut a strip out of a bottle and then use it to do the lashing in a continuous manner.

I'm not going to talk about my plastic bottle strip cutter here; mine is far from perfect and is falling apart but if you'll look over the internet you'll find a plethora of designs and tutorials on how make one... like this one... it's just a randm one I chose.

Anyways. Cut enough of strip of about 1-1,5cm wide. ANd don't ask me how exactly I applied it... I just used the intuition to do the thing. But to finish the lashing just tuck the working end under some previous loops before blasing everything with the heat gun.

And it'll finish the flask.

Step 17:

Ok, so this design is something that emerged from me tinkering with plastic bottles. In my previous instructable, where I made a sturdy flask by laminating multiple layers of plastic material I used tahat reflective film or foil between the layers which produced some interesting aestetical features. But themn I wondered what else can I laminate between the layers to obtain some new qualities of the material. And I decided on something insulating.

Obviously, plastic bottles are really suck at holding really hot stuff so the glass bottle was chosen as a core container. Obviously this kind of bottles isn't ment to be used for containing hot liquids but I just dumped a bunch of boiling water on a three of them just for a test, and, although they were initially a bit chill in terms of temperature nothing happened. So it can be used as a prop but alo quite practically if needed. I did not test how good they hold temperature yet.

And if you didn't figure it out - the protrusions on the sides are for attaching the sling. They turned more towards the back deliberately to accomodate the curvy nature of human body. And the one in the middle... I just like it to be there... looks special.

Anyway, I reckon I could've made this particular one flask a better... I even thought to remake everything from scratch cause I don't like certain blemishes that occured and design choices I made... But it'd mean me going literally dumpster-diving cause I'm currently out of kind of bottles I need for that.

I may revisit this design later, but for now it's it for now, thanks for your attention and I'll stop rambling... Now.


Look at my plastic bottle mace.

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