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FUNCAP shows that the circular economy can be made superelliptical.

Photo of Soren null

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Approximately 19 Billion LEGO components are produced every year. LEGO bricks are one of those things that never break and most people pass them down from generation to generation. Why? Because they're of great quality and fun to play with!

Every year, 200 billions of plastic bottles are used for water but only a fraction of the caps are recycled. Why? Because they are pretty much useless after the bottles have been emptied. What if they weren't?

Maybe if the caps could also be used for something else fewer might end up being tossed away! 


Our proposal to get rid of plastic caps becoming garbage and polluting the environment is to design them to seamlessly work as a LEGO component after the early retirement from their bottle sealing careers. 

Thereby, the life cycle goes from 10 minutes of usage (while drinking from the bottle) or 1 year (the usual shelf life of bottled water) to years and even generations of play-time with the toy. (A fun fact: The LEGO bricks used in the photos are around 40 years old. The plastic screw caps are around 1 months old.)

Some call this approach "upcycling". We call it the Superelliptic Economy!


FUNCAP combines the desired properties of a plastic screw cap (such as tight seal, easy to press down on the threaded bottle neck on the filling production line, easy to open by hand) with the properties of a LEGO brick (such as high quality, fine tolerances and perfect mechanical connectivity with other LEGO bricks).

FUNCAP is made in different shapes and sizes. However, a round shape facilitates its introduction in existing bottle filling production lines. Plastic screw caps come in different diameters (e.g. 38mm, 35mm and 28mm). As the most commonly used plastic screw cap size is 28mm, a 4x4 knob LEGO brick (31.8mm width) provides a good starting point for the first FUNCAP.  

FUNCAP is a keeper

Currently, there are more than 80 pieces of Lego bricks in existence per person on planet Earth, and there are LEGO fans (of all ages) everywhere! 

It is therefore very likely that avid LEGO builders (and their relatives) will see the benefit in actively collecting FUNCAPs and adding them to their brick collection. 

As Trevor and Benjamin, young parents in Minneapolis, USA, said to us sometime in the future (sic!), probably around June 2018, about their two kids:

"They collect the FUNCAPs – not only from their own bottles, they also collect FUNCAPs from others."

high Social Return on Investment (SROI)

Other than being an obvious immediate benefit to the kids that love to play with LEGO, the economical benefits of FUNCAP, despite a (likely) increased unit cost, are obvious as it combines the utility of the screw cap and the LEGO brick.  

Both caps, as well as LEGO bricks, have some initial costs associated with manufacturing. However, the plastic screw cap only creates value for a limited period of time. all components have eventually a disposal cost (not shown). The quantitative value of the long-term benefits of stimulating learning is difficult to estimate - but the "Net Present Utility" is positive.  


Four things are needed to make FUNCAP happen:

  • Scale (in order to reach a reasonable unit cost level)
  • Reach (distribution of FUNCAP)
  • Materials (choose the right materials properties to do the job) 
  • Innovation (access to Intellectual Property Rights in combination with the willingness to try something new and bold)

The table shows some Plastic Screw Cap solutions (as well as the pure LEGO brick):

The "Perma Cap" (which comes in many shapes and forms - 'many patents, no products') initially looks great (and reminds of the  stay-on tab for aluminium cans). However, it is often necessary to separate the screw cap (made of HDPE or PP) from the bottle (made of PET) in order to recycle both. The initial benefits become, when looking at the total supply circle, a huge disadvantage. 

The idea of turning bottle caps into LEGO bricks is not new. A Brazilian company introduced "Clever Cap" to the market but the product has no presence or traction. It seems that none of the Value Barriers were properly addressed. 

The materials selection for FUNCAP is "TBD" (To Be Decided). The decision on which materials to use is not a trivial one (and is a value barrier). However, what is clear is that by combining two functions into one, a lot of plastics is saved. In this case from 9 gram to 5 gram or a reduction of 44%!

VALUE BARRIER: Reach and Scale

If you have Reach, you can Scale your production and thereby enabling economies of scale for lower production costs as well as broader and faster adoption globally. 

The global bottled water market is estimated to grow by 8.5% and reach a value of $ 280 Billion by 2020.

As it happens, the key players in the global bottled water industry include Coca-Cola Co., PepsiCo Inc. and Groupe Danone. All of these companies are participants in The New Plastics Economy Initiative. All companies have Reach. All companies can Scale. 

As Emmanuel Faber, CEO of Groupe Danone, states in his 2017 endorsement of the Initiative: 

"Resources management should not be summarized as a matter of cost optimization but as a powerful driver of shared value creation. [...] I am excited that Danone is taking a leading role in this initiative to help drive systemic change."

"Cost Optimization" deals with Year 1 in the Net Present Utility" graphs already mentioned. "Value creation" is related to the Net Present Utility. Consequently, FUNCAP is fully aligned with the mindset of (at least) one of the leading players in the bottled water industry.


LEGO bricks are made of ABS plastics whereas a plastic screw cap is made of HDPE (or sometimes PP) plastics. Sometimes, an additional material is in-molded into the cap as a gasket. It is not obvious that ABS can be substituted by HDPE or visa versa. New materials could also be explored depending on desired lifespan for the FUNCAP to serve as a play piece. 

Fortunately, the LEGO Group has allocated substantial resources to materials development: In 2015, the LEGO Group established LEGO Sustainable Materials Centre in a significant step up on the 2030 ambition of finding and implementing sustainable alternatives to current materials. LEGO Group owner Kjeld Kirk Kristiansen says:

"The investment announced is a testament to our continued ambition to leave a positive impact on the planet, which future generations will inherit. It is certainly in line with the mission of the LEGO Group and in line with the motto of my grandfather and founder of the LEGO Group, Ole Kirk Kristiansen: Only the best is good enough”.

If the cost price constraints on screw caps for bottled water is loosened, it is likely (assuming that appropriate economic and human resources are allocated) that a suitable material for both bricks and caps can be identified.

VALUE BARRIER: Intellectual Property RIGHTS (IPR)

Rather than using (inferior) designs that might infringe on LEGO's intellectual property (and thereby limiting the reach of them), we propose to do FUNCAP in cooperation and understanding with LEGO. 

Possible IMPACT

Is FUNCAP possible? Yes! But only if the value barriers are overcome. Not by Hans and Soren but by the leading companies in the industries of toy building blocks and bottled water. 

Can Hans and Soren forge a strategic alliance between LEGO and Danone? Probably not. 

Can The New Plastics Economy Initiative, Ellen MacArthur Foundation, International Sustainability Unit and Wendy Schmidt do it? We hope so.

"Only the best are good enough."



Music: Enthusiast by Tours

How does this research relate to our Use Cases?

Trevor & Benjamin (Young parents in Minneapolis, MN, USA), June 2018: “We love taking the kids out to the park during weekends. We almost always bring something to drink. Since Danone introduced the FUNCAP, our kids ask for us to bring bottled water only! They collect the FUNCAPs – not only from their own bottles, they also collect FUNCAPs from others. The only difficult thing is to explain to them why not all packaging can be upcycled or recycled!

What is a provocation or insight that might inspire others during this challenge?

Sometimes, very little has to be invented. Things just have to be combined in a new way. The successful implementation of a Superellipitical Economy Thinking (example: FUNCAP) requires that different companies work together "for the greater good". The world of business simply does not work like that. Even the spell checker suggests that we change 'Superelliptical' to 'Surrealistically'!

Tell us about yourself

Hans is Swedish and currently works for an automotive company in Sweden but has previously introduced beverages with plastic screw caps in Brazil. Soren is Danish and lives in Brazil. He develops businesses and products. He used to purchase plastic screw caps for a nutraceutical company.


Join the conversation:

Photo of Pavel Merkel

Good idea.

Photo of Soren null

Thanks! The FUN(CAP) continues in the "idea section":

Photo of Steve

Hi Hans and Soren,
This is a brilliantly obvious idea that has been hiding in plain sight! Inspiring!
Your submission is also well thought out and presented. Have you had any contact with LEGO?

Photo of Soren null

Thanks for your kind words. We'll wait for the feedback here before deciding if/how to move forward!
Hans & Soren

Photo of Kate Rushton

Hi Hans and Soren,

This is a really interesting product. Have you explored alternatives to conventional plastic materials? Are there other Lego-like products that could potentially be used as an alternative? I found this article - - but I am wondering if there are better options.

I am tagging a few people here who I think would be very interested in this post - Pavel Merkel Purvish Shah Lorne Mitchell Christel Tardif Paricha Duangtaweesub 

The ideas phase opens in 5 days time. I hope you will repost your idea there.

Photo of Soren null

Hi Kate,
Thanks for your comments.
- Honestly, plastic is fantastic! We have not been able to find alternative materials. However, as stated, companies like LEGO are investing a lot of time and resources in the area.
- In order to have an impact, you need to work with the market leaders! The market leader withing construction toys is LEGO. Further, FUNCAP is not intended to be a LEGO copy, FUNCAP is intended to be LEGO!
- We hope that we can just push a 'magic button' to enter the idea phase!?

Photo of Kate Rushton

Sadly it requires a new submission post. However, you can create a skeleton of an idea post and tag me in the comments section and I can 'cut and paste' the information from this post onto the new idea post via the backend of the website.

Photo of Soren null

OK, thanks! :)

Photo of Kate Rushton

Can I just check something? Am I right in thinking that the FUNCAP uses more plastic material than a conventional cap?

Photo of Soren null

Thank, Kate, for your interest!
In the overview we state that a Screw Cap weighs around 3 gram (measured value) and a FUNCAP around 5 gram ("guesstimate"). Part of the difference is due to the fact that ABS plastics is around 15% more heavy than HDPE plastics per volume unit. However, LEGO bricks generally do seem to be more sturdy and thick-walled than Screw Caps (i.e. more plastic used). So our first answer would be that you're right! That also influences the initial cost (as shown in the SROI graph). Our second answer would be that you're wrong! In order to seal a bottle and play you would need a Screw Cap (3 gram plastic) and a LEGO brick (6 gram). You get both functions in one FUNCAP (5 gram). So if we neglect the specific weight difference between different plastics, you save 4 gram of plastic! That's a plastic materials saving of 44%!

Photo of Paricha Duangtaweesub

Thanks for the tag Kate Rushton this is a very interesting idea indeed. I love the concept of play embodied by Lego and finding different instances of play while being ecologically-minded :)

Photo of Soren null

Thanks for your kind comment! :)

Photo of Soren null

Hi Kate, we made a new draft in the idea section... You mentioned that you can c/p the content to there (including the hyperlinks). If so please do!