Introduction: HDPE Blocks From Plastic Bottles

Picture of HDPE Blocks From Plastic Bottles

Hi everyone!

In this instructable I'm gonna show you how to recycle HDPE plastic bottles and jugs to create blocks that can be used in lot of different ways.

Every day each of us uses and throws away lot of plastic stuff...let's change this!

Dave Hakkens (which I suggest you to follow and check his job) is an awesome guy who made lot of videos about recycling plastic. He shows you how to collect, melt and work plastic stuff in order to create new things. In his videos he also shows how to build machines to shred, extrude, inject and compress plastic but if you just want to start recycling a couple of bottles, you can follow this quick guide to do it at home in a very easy way.

P.S. I entered this instructable in the "Plastics Contest" and in the "Reclaimed Contest". If you like this guide please vote for me! I really appreciate it!

Step 1: Materials & Tools

Picture of Materials & Tools


- HDPE bottles and jugs

- scrap wood (for the mold)


- clamps

- baking paper

- high temperature resistant gloves

- scissors / utility knife

Step 2: The Mold

Picture of The Mold

You don't have to get crazy building the mold.

Since we are going to melt the plastic into a block we just need a simple box. The more accurate will be your box, the more accurate will be your HDPE block.

As you can see from the pictures above I used scrap wood that was laying in my workshop, and I covered every inner surface of the box with baking paper. This will be important later in order to remove the HDPE block from the mold. Wood is a porous material and melted plastic is a very sticky material so you don't really want that they come in contact.

Step 3: How to Cut the HDPE Bottles

Picture of How to Cut the HDPE Bottles

First of all HDPE; what's that? how can u recognise it from all the other type of plastic?

HDPE stands for high density polyethylene. It's a quite common material used specially in the production of plastic bottles and corrosion-resistant piping.
As you can see in picture#1 you can easily distinguish it from other type of plastic thanks to the number "2" as its resin identification code.

After removing the labels and washing the bottles from beverages and soaps residues we need to cut them into small pieces. The smaller the better since they'll take less time to melt. You can use a utility knife and a strong pair of scissors to do that.

I usually start with the utility knife by cutting away the neck (photo#2) which is the stiffer part, then I cut away the base, and finally the handle.

To finish the job you can use a strong pair of scissors to cut the bigger pieces into smaller ones (photo#4)

Step 4: Bake It

Picture of Bake It

Each type of plastic has a different melting temperature.

Dave Hakkens did a great job studying every type in order to individuate the right melting point (you can see his job here).
I found out that in my oven HDPE usually melts around 180°C.

While preheating the oven, put your a piece of baking paper onto a baking pan, and place your cut pieces onto that. Finally place the baking sheet in the oven and check it every 10 minutes.

Step 5: The Marble Effect

Picture of The Marble Effect

The first pattern that I'm going to show you is also my favourite one; the Marble effect.

After 10/15 minutes if you see that the plastic looks sticky you can remove if from the oven. Use a pair of heat resistant gloves and rotate the HDPE (with the left hand rotate it clockwise, and with the right hand in the opposite direction) than fold it in half and do another rotation (photo#2/3).

Be quick (it cools down quite quickly) but pay attention! It is really hot and sticky.

Once you get something like what you can see in picture#4 you can put everything back in the oven.

WARNING: Use the gloves! If it ends on your skin wash it immediately with cold water to reduce the pain.

Step 6: Clamp It

Picture of Clamp It

After 10 minutes you can take it out of the oven and you can put it inside the mold.

Clamp it as hard as you can and come back every 5 minutes to tighten the clamps. HDPE shrinks while it cools down so in order to get a flat block you have to tighten the clamps frequently.

Step 7: The Marble Block

Picture of The Marble Block

Here it is the result after 2 hours of cooling down.

As you can see from the pictures the twisting-rotating technique that we used before created a beautiful marble effect. I really like this method because you can see all the different colors used.

Step 8: The "Camouflage" Effect

Picture of The "Camouflage" Effect

This is another pattern. I call it the camouflage effect.

This is easier and safer than the marble effect because it doesn't need to be worked by hand.

Like in Step5, after 10/15 minutes, if you see that the plastic looks sticky you can remove if from the oven.
This time we will use the folding technique. Always paying attention (and always using high temperature gloves) lift the baking paper on one side and fold the plastic on itself (photo#2).

Repeat it on the other side and put it back in the oven.

Step 9: Clamp It

Picture of Clamp It

After 10 minutes of baking, remove it from the oven, fold it one last time making something like a chinese spring roll (photo#1) and put it inside the mold.

As seen in Step6, clamp it as hard as you can and come back every 5 minutes to tighten the clamps. Then leave it to cool down for a couple of hours.

Step 10: The "Camouflage" Block

Picture of The "Camouflage" Block it is the result. As you can see it looks like a camouflage pattern.

Step 11: What Can You Use Them For?

Picture of What Can You Use Them For?

These blocks are incredibly strong, stuff and heavy. You can use them in different ways.

In this photo#3 you can see that I made a knuckle punch, a fidget spinner, some keychains and a spinning top. As said in the Intro, you can check to see other products and techniques to apply to HDPE like the cool HDPE kitchen tiles of photo#1.

Step 12: DIY Spinning Top Toy

Picture of DIY Spinning Top Toy

Here it is an example of what you can do with a single bottle of soap.

First of all I removed the label and I washed very well the bottle getting rid of all the soap residues. Then I melted the plastic into a thin block (following the method shown in the previous steps), and I flattened it with the router until it reached the thickness of 5mm (photo#2).

I drawed a quick spinning top made out of 3 pieces, and I glued the template to the HDPE block. I cut all the pieces following the lines with a scrollsaw, and I sanded by hand all the edges to remove imperfections.

After 2 hours of transforming the HDPE bottle into a block, and after 20 minutes of working on it, I ended up with a cool disassemblable spinning top.

I hope you liked this guide and I hope that you will try to recycle some plastic bottles transforming them into new cool objects.

Thank you for reading my Instructable. ;)
Feel free to comment and ask if you need to know something!



hyjynx (author)2017-11-18

this is Fantastic!!! We use a lot of plastic at my house and i hate throwing it in the dump now i can recycle into cool things for my family and friends.

AmeerH24 (author)2017-11-12

hi can this be used to build houses like an alterntive for bricks

HEARTH ROBOTICS TEAM (author)2017-11-11

Do you think the Blocks are strong enough for a knife handle?

CoconutPi (author)2017-11-09

Would it work if I put the plastic pieces into a baking tin and heated them in that until they soften, and then just let it cool before removing from the tin?

HelenaTroy (author)2017-10-22

Question: I have a load of bard plastic cutting boards which are too cut-marked for me to feel safe using them for food. Could these be sort of semi-melted and resurfaced? or totally recast as new boards? Thanks!

jimgarbe (author)HelenaTroy2017-11-06

I worked in the food industry for a while. I wouldn't try to heat up this type of plastic. Most of the cutting boards are nylon rather than HPDE (totally different). I'm pretty sure the convention is to use direct bleach to clean, and sand with a belt sander if needed. ;-) BTW, nice cutting boards! What's your favorite knife?

FunkyHoratio (author)HelenaTroy2017-10-22

Interesting idea. You could just try putting a piece of baking paper on one and ironing it with clothes iron. Do it out side and with a face mask on, if you have one, to avoid possible fumes.

HelenaTroy (author)FunkyHoratio2017-10-23

I can't see my comment on that post, so I can only reply to comments that have hit my "your comments" page. Can't find your name on the thread comments, either, nfi what my pc is doing now!

I don't have a planer, not even a hand-plane, so I very much doubt that I'd get anything like a regular surface. I'm not so much low-tech as no-tech

I have a small heat gun, might that work? at least to soften the surface layer to re-lay or re-cpver? [I also have a rolling pin!]

FlorinJ (author)HelenaTroy2017-10-22

In the same vein as the one suggesting ironing the boards through a sheet of baking paper, you could roll over the baking sheet with a somewhat thicker iron rod heated a bit - not red hot, that would melt the plastic completely.

I wouldn't expect a thickness planer to leave plastic completely smooth. Plastic chips differently than wood, I'd expect sort of a grainy texture, almost smooth but not quite, to remain on the board.

What you could also do is spread some acetone on the board, and let the board dry out slowly after brushing the surface with a soft paint brush. Acetone dissolves polyethylene, brushing across the board with a soft paintbrush would probably dissolve the rough edges standing out of the surface and fill the grooves with the resulting solution.

Maybe try running them through a wood planer? But that's just me guessing.

Goose (author)2017-11-05

How tough is the block? can you cut it with a knife? Saw?

could I fabricate brackets or levers from a solid block?

Ricardo Furioso (author)2017-10-31

Excellent work.
Responsible and generous of you.
Thank you for sharing.

fitrasony (author)2017-10-24

I've always had my curiosity about how to simplify Dave Hakken's rather complicated machinery, but you sir, made it looked so simple by using an oven to melt the plastic. Your I'ble is truly a mind opener for me as I'm still looking for an alternative material..

Thank you..

manuelmasc (author)fitrasony2017-10-30

so nice to hear that! thanks

SNEHALCHEVLI (author)2017-10-24

Well Done.. :)

manuelmasc (author)SNEHALCHEVLI2017-10-30


SHAMSUDHEEN MARAKKAR (author)2017-10-24

That's just awesome. Is it possible to melt HDPE into juice so that we can mold desired shapes easily?

If you get it to a pure liquid point, its probably close to combusting. I use HPDE as rocket fuel and its ridiculous hard to cast. Those bottle you see hard use with injection molds at very controlled, hot and high pressured envireoments.

manuelmasc (author)CptPikachu2017-10-30


CaitD1 (author)2017-10-22

As a chemist, I would question the safety of melting the plastic indoors. Toxic fumes are not always obvious. For safety's sake I would recommend a toaster oven outside to eliminate all possibilities of toxic fumes.

CptPikachu (author)CaitD12017-10-26

MP depends on the purity of the HPDE. Number 2 recyclable HDPE is pretty high grade. Off hand gases did pose anything alarming (just make sure your melting HPDE and not PVC :) ). Just buy a toaster oven that you use just for crafting and not food.

RedBinary (author)CaitD12017-10-22

While this can be a serious concern with other plastics, generally only if they are visibly burning and vinyls especially , clean HDPE does not pose any hazard. Any lingering chemicals that were contained in them are a different matter.

CaitD1 (author)RedBinary2017-10-22

I read those MSDS sheets, and they were incomplete. Perhaps they have different standards in the UK. I saw no toxicity report, which American ones do have. I used to be in charge of Hazmat and all the MSDS at our institution. Best advice is what your MSDS said at the bottom. Safety first. I know when I first started in chemistry many years ago, there was very little cautionary info for the chemicals I handled and later we found they were dangerous and even carcinogenic. Back in the day, all we had was a fume hood. My best advice for any project be it plastic, wood, paint or whatever, SAFETY FIRST. As far as no odor detected, remember Carbon monoxide is odorless. Again better to be careful than sorry.


snowf7 (author)CaitD12017-10-23

CaitD1; I have to agree with your "Safety First" reasoning. Since we became bird owners more that twenty years ago, we have gotten rid of all no-stick bake-wear. When Teflon coating is heated there are gases released that are known to kill pet birds. As much as I would enjoy this project, I would not take the risk with my parrot. I would only try this with an outdoor oven. We have spent more than 18 years together and I would never forgive myself if fumes were released that could cause him any harm.


RedBinary (author)CaitD12017-10-22

I just linked to the first relevant info that I found - I didn't even see any SDS/MSDS there. I am actually in the USA and have worked in HDPE processing for around 25 years. If you look at an SDS for HDPE (which we go over once a year in an OSHA required meeting) you will see that it is totally inert in all states and the greatest risk of harm can come from inhaling excessive amounts of fine dust created when processing. This is a mechanical issue and not one of toxicity. The plant I've worked in for the last 15 years is actually a member of the OSHA Safety & Health Achievement Recognition Program (SHARP) and means we're audited for policy and procedure twice annually. The only safety gear we're required to wear while working all day in a plant of 10 large machines all heating HDPE to around 350F are standard hearing and eye protection.

As I said, though, residual chemicals from poorly washed bottles would be a separate matter.

santiagoS23 (author)CaitD12017-10-22

As chemist i actually think u don't longe anything about plástic. HDPE fluence temp ia aaround 130 *c and appart fronteira coloring masterbatch its Really rare to put any other help proccesing agent. And it compromises the recicling label 2. And from the 3 types of PE (Low density, linear, and high density) the hdpe has the higher degradation temp.

CaitD1 (author)santiagoS232017-10-23

I realize your comment is not in your native language, I did not quite understand what you were trying to say. My specialty was not in plastics but biochemistry. I think you said I didn't learn or know anything about plastics but I am not sure. I have worked with plastics for a very long time. My rule is Safety First. They told me all those fumes I was breathing was safe, only to find out years later they were not. Why take a chance and find out that the plastics emitted some non-detectable fume when melting. Always err on the side of caution.

oky jim (author)CaitD12017-10-22

At around 180 Deg.F. you are not melting the HDPE, just softening it. I have never noticed any fumes at this low temperature.

RedBinary (author)oky jim2017-10-22

It's 180C or 356F

TammyT5 (author)CaitD12017-10-22

As a BSN RN, toxic fumes was my 1st thought. Thanks for bringing it to everyone's attention.

InarcoC (author)TammyT52017-10-22

I wonder if this will leave carcinogenic/toxic particles inside the oven, in addition to the toxic fumes. Toxic fumes do not always smell "toxic" (PLA fumes smell as sugar candy, despite of their small particles being an agent increasing risk of COPD).

CaitD1 (author)InarcoC2017-10-22

I use polymer clay for crafting. It advises strongly not to let the clay "fire" on any surface that will be used for food and it is also advised to use a toaster oven dedicated to the clay to prevent cross contamination. The package says non-toxic, but why take a chance?

WonseokC (author)CaitD12017-10-22

I agreed with this comment.

Tangski (author)2017-10-26

Very nice sir! I think it would also make some very nice knife handles too:) I would however take it outside...not sure, even after reading below it is safe enough to do inside.:) GREAT recycle idea for sure!!

alexeicharkham (author)2017-10-23

Just awesome!!

thank you

treymartin82 (author)2017-10-23

How would something like this hold up if made into large tiles for the floor of a tiny house camper?

manuelmasc (author)treymartin822017-10-24

just don't make them all white or you'll see the dirt accumulating in the little scratches that you will unavoidably do by walking on it.

manuelmasc (author)treymartin822017-10-24

I think that it would hold up perfectly for years! It has a quite high melting point that your camper would not reach even in the hottest summer, plus in commerce there are tiles and floor stuff that are made of HDPE. It's a very strong material and is used for this property in lot of applications (even for long outdoor uses for example think about the 55 Gallon Water Drum )

dirk.medema (author)treymartin822017-10-23

HDPE is plenty tough, and should be more than adequate for your tiles.

DaveB201 (author)2017-10-23

Two comments:

I've never been able to make the gloves work. The reason is that the plastic is so sticky that it sticks to the gloves too much to make much other than a complete mess. Not to mention that the gloves are useless afterwards.

The other issue I've found is that all HDPE products contain plasticisers. Liquid components that reduce the melting point, among other useful properties. Each cycle of reheating evaporates more of the plasticiser and raises the melting point for the next cycle. So, in my experience, you only get one really useful shot to make a useful block. (And yes, fumes, whether you can smell or not. Best do outside.)

JimW54 (author)2017-10-22

I would be more concerned about fumes from residual chemicals from the container contents during melting, not so much from melting consumer plastic containers itself. Now burning plastic would be different, I would be concerned about maybe dioxins being released etc.

manuelmasc (author)JimW542017-10-23

Yeah but if you wash the containers before melting (as I suggested in the ible) you can melt plastic without any fume/smells.

JimW54 (author)manuelmasc2017-10-23

I know, some people were worried about the plastic giving off fumes, and I wouldn't be if they were cleaned.

MichaelandDebbieM (author)2017-10-23

is it possible to just heat up the plastic to 200c and have it melt to the point it is more like a liquid? thanks

I don't know for sure, but I think it will start to smoke & burn if you heat it to 200°C (392°F). I wonder how hot it can be heated before it starts to burn.

Mark 42 (author)Mark 422017-10-23

There's quite a bit of info here:

I never tried that... but I don't think that you could reach a "liquid plastic" point

DavidH752 (author)2017-10-22

How about polyethylene (plastic bags)? Have you played with them?

manuelmasc (author)DavidH7522017-10-23

I never tried with those but I saw this instructable a couple of years ago

About This Instructable




Bio: Italian maker, law student, DIY enthusiast. I make lots of projects, I fix lot of stuff and I like to save and reuse materials taken ... More »
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