Introduction: Coffee Cup - Honeycomb Sandwich Structure

Picture of Coffee Cup - Honeycomb Sandwich Structure

So you think your coffee is strong? Wait until you have tried your coffee cup!

"A Honeycomb core is an array of hollow columns made of sheet material which is used to separate the two facings of a sandwich structure".

So why not make one of Coffee Cups and enter the Coffee Cup Challenge?

This I'ble will show you how to make a honeycomb panel as a building block for your future projects.  If you like it, don't forget to vote for me!

Where I live, paper cups are somewhat rare, so I have merely made a beam and tested it. 
My project has ended by testing this beam. If you want to take it to the next level or if you have an awesome idea, feel free to use this information and even post it in the Coffee Cup Challenge as well (some credits would be nice though).

Step 1: What Do You Need?

Picture of What Do You Need?

It's a great misconception that you need fancy materials to fabricate composite materials. Nature is full of extraordinary examples.  

You will need:
* 45 coffee cups
* two triplex strips of 90 x 20 cm (thickness 2 mm).
* Glue.

The dimension of the strip was more or less determined by the fact that I could only get hold of 45 cups (3 rows of 15 cups).

Step 2: How It's Made.

Picture of How It's Made.

1. Apply glue to one side of the first strip (preferably with a brush)
2. Place the cups in an alternating pattern.
3. Apply glue to the second strip and place it on top of the cup.
4. Add lots of weight.

Step 3: Testing.

Picture of Testing.

As expected, the beam is very light (900 g). 
The test dummy on the picture (me) weighs 80 kg.

Picture 1 & 2
As expected, with pure compression, nothing much happens. Not a crack.

Picture 3
Now it became critical. Upon mounting I could hear some cracks (didn't stay too long on top). 

Picture 4
I mounted again with two feet and told the photographer that I would lift my left foot on the count of three. He had to push the button at the same time. The structure collapsed almost immediately.
I was very lucky because: the picture is perfect and I didn't strain my ankle.


Step 4: Room for Improvement & Applications

Picture of Room for Improvement & Applications

I believe you can really make a strong structure with these materials, however there is room for improvement:

1. Arrange the array of cups more neatly (symmetrical).

2. When I applied the glue, I noticed that a lot of it was absorbed by the triplex. Therefore the bond with the cups was likely to be less strong. I neglected this fact.

3. I Added approximately 70 kg of weight where I should have used a vacuum bagging technique. This could have easily increased the "weight" tenfold (700 kg spread evenly). This was a deliberate choice as I wanted to keep the project simple.

4. Some of the coffee cups didn't have a flat surface anymore. Apparently, people often bite in these cups. This reduced the bond as well.

5. In the previous step you can see that one block (on which the beam rested) was slightly higher than the other one, resulting in high local tension probably.

So should we phone NASA and tell them that we have the new building block for their next spacecraft?
It all depends on the confidence that you have in your production process. 

Definitely: tables, doors, panels, hatches, shelfs
Probably: light construction elements.
Unlikely: aerospace!


IOPort51 (author)2011-08-18

this is great, good thinking! I think these would not be as thermally resistant or as strong as SIP's but a lot more cost effective for a lot of purposes. I am thinking about farm structures, chicken houses, rabbit hutches, small barns. Not taking away from the Styrofoam cup concept but free association brings me to the next obvious choice being aluminum drink cans. You could set a house on one of those!
I am looking forward to your next project, whatever it may be.

bertus52x11 (author)IOPort512011-08-18

In the discussions on the main page, you can find a discussion about using aluminium cans (Coke).

Biggsy (author)2011-06-06

You know.. i think i'm going to set this as a challenge for my Scouts! hehehe

bertus52x11 (author)Biggsy2011-06-06

Pay very much attention to the glue bond between the cups and the skin. This is the most important aspect of the strength!

Show us the results when you're done!

Biggsy (author)bertus52x112011-06-06

I shall do :)

Kryptonite (author)2010-04-24

You heard about that group that made a bridge span 5 metres, that held 200kg and was made of paddle pop sticks and glue?

bertus52x11 (author)Kryptonite2010-04-25

No. Would be nice to see.

Kryptonite (author)bertus52x112010-04-28

It was on tv a few years back. Can't find a link, goddamn it!

tulekah (author)Kryptonite2010-09-14

there are annual competitions all over the country, and the world, for this. google popsicle bridge competition and you'll find all you want. the great ones are where, rather than unlimited sticks, the contest is to make the strongest bridge with a small number.

Kryptonite (author)tulekah2010-09-17

Some of the results are amazing.

Kryptonite (author)bertus52x112010-09-17

I've looked every where and haven't been ableto find it.

Hiyadudez (author)Kryptonite2010-04-27


tulekah (author)2010-09-14

this is a TORSION BOX, way way cool. i'm thinking of two sheets of glass bound by epoxied glasses!

bertus52x11 (author)tulekah2010-09-14

Just do it! Would be cool, don't forget to post it.
(alternatively, use Gorilla Glue, enter the Gorilla Glue competition and win some of the prizes...)

yoshhash (author)2010-04-21

 If you filled the voids (outside the cups, not inside) with expanding foam, or some other adhesive, light, form-filling material, you would eliminate the "weak points", which is the only thing wrong with this very BRILLIANT idea of yours.  Not only that, but it would then be an insulating material. 

tulekah (author)yoshhash2010-09-14

expanding foam expands and will dent the cup walls. this is like the old "stand on a pepsi can" trick.

bertus52x11 (author)yoshhash2010-04-21

That's just one step away from getting rid of the cups all along and to go for a foam core!
However, I think your suggestion could work and your point is that there is room for improvement (as stated by myself in step 4 of this I'ble).
Only thing is, currently I don't have the time nor the resources to take it that step further (hope that someone else will. you?). That's why I made the remarks in step 1 about the contest. I'll be happy to contribute.

Oh yeah, air is one of the best insulators around!

cogni (author)2010-05-02

What is a "triplex strip"? 

Could one just use corrugated cardboard? 
If so, coroplast would also work (corrugated extrusions of plastic) but it is more expensive.  $10 for an 8' x 4' sheet here, from a sign shop.

tulekah (author)cogni2010-09-14

dumpster dive cardboard boxes. cut into 4" strips (cut across corrugation) and roll (pop-can) into tubes, glue between face cardboard strips (the corrugation lines should run parallel to the longest dimension.
you can make the faces stronger by doubling the face, or by cutting the faces on the bias with the corrugation at right angles to each other.

bertus52x11 (author)cogni2010-05-02

Triplex is just plywood (so I have learned in the discussion at the intro of this I'ble).
I guess you could use cardboard, just as long it doesn't get wet (but then the same applies for the cups!). The skin of the sandwich panel must withstand tension and compression. So the cardboard may not be too thin.
Coroplast might work as well, but seems a bit expensive? (but will paper adhere to plastic?) If money is no problem, I would get rid of the coffee cups all together, but then that's not so much fun!

beehard44 (author)2010-07-27

why not put scrunched up paper as filling in the coffee cups to make them stronger? maybe slather the sides with concrete for building material? just suggesting

Stevie89 (author)2010-07-01

Coffee cups hard too find? lm a Canadian.. in my city, Saint John NB, we have like 25 Tims alone, 3 starbucks, 4 Java Moose.. coffee cups are EVERYWHERESSSSS :-S

zeeebus (author)2010-05-09

I was thinking the same thing about the walls.  Much like a SIP, but homemade and less styrine. 

I can imagine building a 8' tall frame using studs the same width as the height of the cup (If cup is a medium, it will be xx inches tall, therefore your stud should be a 2 X xx inches wide stud.). 

Put studs on 4' centers. (4' is probably too wide actually.  I think, you would have to place them just inside the width of the plywood so when you are actually attaching the panels to the framing of the house you can nest the panel into the framed wall bay and nail the existing frame to the panel frame.)

Temporarily screw a sheet of 4x8 OSB onto the frame and flip it over so the OSB (Plywood) is on the bottom of the frame. Lay the frame at a slanted angle (the laying angle of a drafting table, say). 

The angle would allow you to stack cups onto the entire field of the plywood between the studs with cups. 
Next, you would take a second sheet of OSB and, using a roller or air pressurized sprayer(not disposable aerosol type, but the kind used in finishing booths at furniture and body shops), coat the ply with laminate adhesive according to manufacturers instructions. 

Apply this sheet (when it is good and tacky and ready) to the frame.  Screw it permanently to the studs. Ideally (I'm making this up as I'm typing, so bear with me here) Ideally the contact of the cups onto the glued surface would be pretty uniform.  Maybe a stud that is just a hair narrower than the height of the cup would allow for the adequate uniform pressure to contact all the cups.  I guess you'd have to be careful not to crush them, though.

Next, you would flip the entire 4x8 coffee cup "sandwich" over so that the adhesive coated plywood is on the bottom. 
Remove the first sheet and coat appropriately.  Re-attach to frame, and VOILA!  You've just made your own Coffee Cup SIP! (Oh, (S)tructural (I)nsulated (P)anel)

The load is carried on the studs.  I think...By all means, use at your own risk... Any engineers out there should  probably put me in my place here.

I think the real SIPS have the studs a small distance from the edge of the ply, which allows them to nest with a second stud already attached to the bottom plate of the wall (the horizontal 2X___" that is already fixed to the floor of the structure)
Any thoughts?

Just a thought. 
Great Instructable!!

bertus52x11 (author)zeeebus2010-05-11

Looks like you have written an Instructable! Add pictures and post it, I would like to see it! ;-)

zeeebus (author)bertus52x112010-05-20

Darn.  I was afraid that was what was happening!!!

Thanks for the reply.  Guess this gives me the summer project I was wondering about.  We'll see.  I would really like somebody to tell me if this sort of thing would be dangerous at all.  I'm concerned about structural soundness primarily, and fire secondarily.  Anybody???

By the should have definitely beat the coffee cake entry and winner.  I didn't read any of the comments on the thing because I didn't think it was all that great of an idea.  Now that I've looked at it, I'm wondering if the wax on the inside of the cup wouldn't enter into my reproductive system, or some other remarkably unfortunate place!!!

I'll start collecting cups and stuff for the SIP.

nutsandbolts_64 (author)2010-05-07

 Oh no, I can't find the vote button! Nice project anyway. I'll be sure to make my shelves with those.

Thanks, and post an Instructable if you're done!
I believe voting is possible from May 10th on, but I'm not sure how it works (if you will see a button).

Kiteman (author)2010-04-18

This could make an interesting door or screen-wall, especially if you use transparent acrylic to sandwich the cups.

For a table-top, you would only need the top surface to be transparent.

Well done.

knektek (author)Kiteman2010-04-19

Yes, if you want to look like a poor man who can't afford a proper table. Instead he would have a table made out of coffee cups.

Kiteman (author)knektek2010-04-19

I guarantee that if you made a table like this, and sold it through an agent, you would get well over the price of a standard table.

valhallas_end (author)Kiteman2010-04-19

And Ikea would buy the design and release a trendy Starbucks-y version for twice that amount...

mycroftxxx (author)valhallas_end2010-05-05

 This is where it gets pointed out that the Ikea LACK furniture brand is based on hollow-core door engineering.  Both hollow-core doors and LACK furniture are made from a composite honeycomb material whose walls are usually thick card or thin wood.  

So, in other words, such an idea could only be called LACK-luster.

 actually it's just paper (not that I ripped a door apart; I just saw it on TV) that's the honeycomb material you're talking about, although if it was some composite it would be extremely strong.

knektek (author)Kiteman2010-04-23

it is now futile for me to emphasise the words 'coffee cups' ...

Hiyadudez (author)knektek2010-04-27

It may be cheap, it may seem tacky to you, but to others, it is a work of art, and a sense of taste, which apparently, you don't have.


knektek (author)Hiyadudez2010-04-27

This is a world with opinions. Anyway I was talking about using USED CUPS for this. Not ones that have been drank from. Other than that this is a great project.

Hiyadudez (author)knektek2010-04-28

You didn't say USED CUPS once in all of those comments, so don't play that with me.

knektek (author)Hiyadudez2010-04-28

Well, i'm not playing anything with you. so...


Hiyadudez (author)knektek2010-04-28


Toastalicious (author)knektek2010-04-20

you underestimate art

gmjhowe (author)Kiteman2010-04-19

 You could use it to make completely see through walls and floors if you used plastic cups. Might be easier to get a good bond between plastic and plastic also.

mrmarshall1 (author)2010-04-25

this sort of thing could be used to make walls for houses. it would be strong, light and thermally insualating thanks to the small pockets of air in the cups would provide..good job!

bucklipe (author)2010-04-23

Another aspect to gluing up the project would be to paint on a layer of glue to the boards and let them dry or at least get tacky. This seals the surface so that new glue will adhere better. Do the same with the rims and bottoms of the cups. If you choose to let them dry, reapply glue to the rim and bottom of the cups and assemble and compress it. If you can reassemble it while tacky (not likely), compress it. Re-test the strength after this...

wilmadan (author)2010-04-22

great idea! i think this will be helpful in building a house by filling up the cups with earth and the cups will serve as the blocks.use chicken wires to make it sturdy

faab64 (author)2010-04-20

This is very interesting.
Where I was working before, we used to throw out thousands of plastic cups a day. This could have been an interesting idea to re-use them as building material to make insulated walls.
I have to think of it in the future, it can be fun to use this to use waste in a good way.


JavaNut13 (author)2010-04-19

That is really cool. And I mean really cool. so cool, I might make one.

dchall8 (author)2010-04-19

What is triplex?  Is it a thin plywood? 

lieuwe (author)dchall82010-04-19

 triplex is plywood with three layers, but the term is sometimes used instead of plywood. btw good ible, but ikea has used this type of structure for years, some of their coffee tables use a honeycomb structure made out of paper...

dchall8 (author)lieuwe2010-04-19

Cool!  We call it wall paneling in the most inexpensive version.  Some carpenters call it luan.  You can get very expensive three-ply plywood, too. 

The wood is very absorbent.  You might try Gorilla Glue if you want to do some experiments.  Moisten the wood first with a paint roller dipped in water, apply the glue to the cups (dip the cups in glue), and place them.  Gorilla Glue foams up when it gets wet and expands to fill voids. 

lieuwe (author)dchall82010-04-19

 another way might be getting a large diameter drill and drilling holes part-way trough and squeeze the cups in there

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