HDPE Blocks From Plastic Bottles




About: 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 from broken stuff.

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!

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Step 1: 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

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

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

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

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

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

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

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

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

And...here it is the result. As you can see it looks like a camouflage pattern.

Step 11: 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 preciousplastic.com 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

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!


Reclaimed Contest 2017

Second Prize in the
Reclaimed Contest 2017

Plastics Contest

Second Prize in the
Plastics Contest



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    199 Discussions

    dareel dill

    5 weeks ago

    I'd like to create a block with reflective specks mixed in. My thought was, is it possible to mix glitter or small bits of aluminum foil in with the plastic? I assume the metal flakes would have a higher melting point and would remain sparkly through the process.
    Have you had experience with this or know of any alternatives?

    1 reply

    6 weeks ago

    3 Questions: Would HDPE from pill/vitamin bottles work? Would the pan be food safe after using it? and Could you use PETE?

    Instructables Plastic.JPG

    1 year ago

    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!

    10 replies

    Reply 1 year ago

    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?


    Reply 1 year ago

    so sorry for the delay, took me a while to find your message so that I could answer it. Thanks very much for your comment, I hadn't thought about different plastics and whatevers.

    I usually buy cheap chopping boards which aren't best-quality: to me it's all "plastic" of one kind or another.

    I wasn't really serious about melting and recasting them - I'm visually impaired and have to get so close to my work to see what I'm doing that fume inhalation can't be avoided, and even very slight ones add up when you're that close.

    I just have so many old cutting boards that are ok as boards, just not really properly food safe, they're so badly scored that even if scrub them from every angle I'm still not confident using them.

    hmm, maybe I can stick some together to make a sandwich for a clipboard, or a small tray, or something like that.

    I prefer wooden boards, but mostly use plastic because it's cheaper; I can't use weighty ones, so plastic is the lightest alternative.

    I prefer short kitchen knives; given my vision, it gives me more confidence that the blade won't bend or go wandering off when I'm trying to use it.


    Reply 2 months ago

    The nylon boards once they have deep scratches can be sanitized in a bleach water solution soaking over night. But then again when it comes to food safety, when in doubt throw it out!


    Reply 1 year ago

    hi Helena,

    You can not fix old nylon/plastic chopping boards they are designed that once damegaed you throw away or give it to a woodworker as old nylon/plastic boards are great to make sliders out of and other bits and bobs for the workshop Or you could use them to make a garden border. As that is all they are good for once past their used by date.

    You can not put them through a plainer you will damage your plainer and the chopping board, besides the chopping boards were designed to have a dimpled surface so that will not slide on the bench top or allow the food to slide around too much if kept dry when cutting meat that is.

    I mentioned a use by date above this is correct you can not use them for ever like the wooden boards, they need to be replaced every few years due to the knifes interaction with the surface and over time if the plastic board is not thick enough it develops a concave shape to it and this is one of the other reasons the plastic/nylon chopping boards have to be replaced. This goes the same with the “SoderStream” bottles if you checked the small print on the bottle it will have a date on it for when you need to replace the bottles.

    If you have a dishwasher you can put in there to wash I do that with mine it’s okay but I only use it to cut the cats meat on. In the food industry they use the plastic/nylon boards because they can go into the dishwasher and this will sterlize them and is the only reason they use those types of chopping boards now and not the wooden ones. Wooden chopping boards can not go into the dishwasher as they are glued together with food safe glue and with the dishwasher heating up this softnes the glue to the point the boards fall apart. I know I did it with my own chopping board I had :-) it was a lovely mess to be cleaned out of the dishwasher lol

    As for my food prep area I have a wooden chopping board that’s been in the family for 40 odd years now. It was me Mom’s chopping board and when she passed away I kept it as it is a good quality one chopping board and it’s easy to keep clean. (As I had killed my board in the dishwasher lol)

    Even with the number of years On it it’s still as good as new as we have always had it has sanded Every 6-8 months and I have even put it through the plainer to flatten it out a bit as it is almost 3” thick I don’t think I have to worry too much about it :-) but it does need a light sanding at least twice a year to clean it off in preparation for food safe coating and that’s not cooking oil as it goes sticking with age, you need the correct coating which I managed to get from the hardware store :-)

    I hope this helps :-)


    Reply 1 year ago

    Hi Dawsie, many thanks for your very detailed answer!

    I hadn't thought about garden borders. I don't have any electrical tools other than a cordless drill, so I can't cut them, or shape them at all

    I've thought of using my old boards as base-plates to build small models on, or home-made ornaments, so that they can be wall-hung. I can at least spray-paint them :D.


    Reply 1 year ago

    Your very welcome Helena :-)

    I have been using my as sliders for draws in the workshop to let the draw slide smoothly :-)

    I never thought of using them for small models but then I have a heap of 3 ply high quality ply for mine I use them for my polymer clay models that I make :-)

    Once you start thinking out side of the box you will be surprised at how many things you can use them for :-)

    Have fun creating Angela


    Reply 1 year ago

    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.


    Reply 1 year ago

    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!]


    Reply 1 year ago

    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.

    la xerra

    Question 2 months ago

    hey man of law&plastic, good, yes, plastic is fantastic stuff to get high on.

    q1: did you ever play around using a rolling-pin to make ´sheets´ etc while that goo is still hot/soft?
    q2: did you ever use p.e.t, #1?

    thanks again, and keep melting (burning?) the house down


    2 months ago

    I've been making it into sheets and I had one come out that was a little too thick for my liking. I gave it to a friend that was going to use it for something on his trailer. He came back 5 minutes later and said "I have an idea" we cut it into a small paddle shape and he uses it for automotive work when he need to hammer on something without damaging it. Similar to a rubber mallet but can really take abuse.


    3 months ago

    Is there any other way to melt the plastic instead of heating it in an oven

    1 reply

    Reply 2 months ago

    you can heat small amounts with a heat gun but its very boring. I bought a little oven off ebay for $8 and use it only for working with the plastics.


    1 year ago

    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?

    1 reply

    Reply 4 months ago

    You have to compress them to achive uniformity and a good bond. If not it will be like a plastic sheet of swiss cheese.