Expanding the Organic Material Evolution

Most Common Questions about WillowFlex Premium Eco-Filament


What is WillowFlex

WillowFlex is a Flexible, Premium Eco-Filament made from compostable raw-materials. Makers can print ecological objects that don’t harm nature or the people in the printing area. It is more heat and cold resistant then standard filaments at the same price.

WillowFlex was successfully launched on Kickstarter (151% backed) with supporters from 32 countries worldwide. It is now available in BioInspiration’s Online-Shop in 1,75mm and 2,85mm.

How is WillowFlex produced?

BioInspiration puts a primary emphasis on quality.  We work with experienced production partners to offer WillowFlex to the world! WillowFlex is extruded by 3d-k.berlin in the experimental hub of Berlin. 3dk produces filament for 3D Printing based on 30 years of professional experience in Plastic Production and Extrusion. All produced filament is tested on 7 different 3D Printers in their in-house la. Their primary emphasis is on an error-free and uninterrupted print experience – determined by the material quality and a well-calibrated machine.
Our eco-filament is spooled by Mosaik-WFB in Berlin Kreuzberg, a workshop that empowers disabled persons to work together in a independent and socially protected space.

Why is WillowFlex a game changer?

WillowFlex is the first flexible 3D print filament from compostable raw materials. This unique elastomeric bioplastic is made from compostable raw materials that have passed the U.S. (ASTM D6400) and E.U. (EN 13432) standards for compostability. WillowFlex’s base component is non-GMO corn starch.

Anyone who has tried 3D printing knows the familiar scent of melted plastic in the air. WillowFlex gives hardly any smell and significantly less micro-particles in the air. We envision WillowFlex (and our coming standard WillowFest line in the coming months) will set a new baseline for filaments used in sensitive environments such as schools, homes and kitchen, and medical applications.

What are the EU 13432 compostability standards? What does it really mean?

WillowFlex’s raw materials have been tested against the more stringent EU standards (EN 13432). The test confirms that the material can be recycled through the composting of organic solid waste in an industrial grade composting environment (http://greenplastics.com/wiki/EN_13432) and includes:
A biodegradation level of at least 90% in less than 6 months.
Disintegrability with test material greater >2 mm less than 10% of the original mass
Absence of negative effects on the composting process
Low levels of heavy metals and absence of negative effects through a plant growth test.
The raw material from WillowFlex has additionally met the less stringent U.S. (ASTM     D6400).

Can I compost WillowFlex myself?

Yes – we have also put WillowFlex parts in a standard, backyard composting environment and they also breakdown in 2-3 years.  In order to speed up the process, like with any good composting, the parts should ideally be shredded first to enable the anaerobic process.  Also make sure that the composting is providing all 4 ingredients for healthy composting.

How fast does WillowFlex decompose?

We always like to compare WillowFlex to wood. When it is in a well working compost scenario warm, good mixture of elements, enough air flow and it is in small pieces (ideally shredded) you should expect it to be mostly decomposed within two-three years.  But, like wood – if those criteria aren’t met, it can last a long time!
So if you are using WillowFlex in a normal application, you don’t have to worry – it won’t just start decomposing!

Do you have any already printed objects to show what is possible with WillowFlex?

Yes – you can get access to several prints to get you started here in on Thingiverse Account or here on the Getting Started with WillowFlex page.
On our Youtube-Channel (BioInspiration EU) you can find our introduction video giving an overview of WillowFlex and short-clips of several printed objects to see what WillowFlex can do!  Subscribe this channel to stay updated about further innovative materials.

What possibilities are opened by using WillowFlex? What are its unique features?

WillowFlex is an Eco-Filament that opens new possibilities:

  • Environmentally friendly, compostable
  • Flexible
  • Resilient – heat and cold resistance
  • Strong Layer Adhesion
  • Works with every printer on the market that we have tested so far!
  • Printable on an unheated bed
  • Surface accepts both acrylic and biodegradable water paint
  • Bonds well with PLA

What is your long-term vision for WillowFlex?

WillowFlex offers high-quality material that is moving us towards a decentralized, plant based elastomer that outperforms many of it’s oil-based competitors. But there is still room for improvement. We want to see WillowFlex produced locally from regional plant matter that can be returned to the soil when done. And we want to experiment with other starch sources than corn that are less intensive for the soil. This will have the added benefit of providing different material qualities such as faster decomposition time, different material qualities, etc.

Our immediate goal is to raise the production quantity of WillowFlex to justify opening a second production center here in Europe.


Where can I order WillowFlex?

WillowFlex can be ordered directly from our Online-Store. We will ship within 2 days of receiving payment.

If you are ordering 15+ spools or are interested in larger spools then those shown online, please contact us directly at orders@bioinspiration.eu.

I would like to buy larger quantities of WillowFlex. Do you offer any sales discount?

Yes! We provide individual offers for WillowFlex-user with demand for larger quantities. The first discounts come at 12 spools.  And we can prepare larger spools 1-10kgs which are also available at a discounted rate per kilo.

Do you ship to my country?

Yes – we ship around the world.  You will need to pay for your own shipping and insurance, but we will ship to you! We are also increasingly getting resellers that can sell to you in your own country.  Take a look at the list to see if we are already working with someone in your area.
We also expect to open a US delivery point in the nearer future.


Will WillowFlex work with my 3D printer?

It has worked with all printers that we have tested so far. It works on an unheated bed, so that lowers the access level significantly. It even works with Bowden-Extruder with specific settings. (See the next answer for more details).

Specifically we know that it has been printed successfully on:

  • Makerbot Replicator 2
  • Ultimaker 1
  • Ultimaker 2
  • RepRap X150

If you have a printer that isn’t on this list and has printed WillowFlex send a picture of the print and your printer type to us at info@bioinspiration.eu

What settings can you use for printing WillowFlex work with Bowden-Extruders?

Our filament producer 3dk.berlin solved this question with a contest at a trade show (The Full Story in German). The winners got free WillowFlex!

Cheat Sheet

– Maximum Active Cooling above 2nd layer
– Retract at 100mm/s
– Retract to the filament outside of the suspension area + 2mm
– Soft pressure between the feed and the back-pressure gears
– Consistent print speed (inner/outer/cover/infill)
– Print speed between 30 – 50 mm/s
– Minimum of 10s per layer print-time

Here are the specific settings/tips for printing WillowFlex on Bowden-Extruders:

– Basic advice: Get a good active cooling system for your printer and cool as much as possible beginning with the second layer.
– Everything stands and falls with the Retraction: Retract deeply and quickly to prevent oozing. A retraction rate of 100mm/s should work.
– You will also need find the maximum retraction distance: retract until the suspension of the Filament is hidden in the hose, and then and 2 mm further. We tested on the NBEO printer and the depth was 6.8mm.
– Don’t squeeze the Filament! WillowFlex offers a very good grip on the feed wheel. So you can adjust the pressure of the gears to be very gentle.
– Print with constant speed (inner/ outer cover & infill). We got the best results with 30mm/s – 50mm/s.
– We recommend a minimum print time of 10 seconds per layer.

Will WillowFlex feed well through the plastic guide tubes?

Yes. We produce the filament here in Berlin specifically to ensure the quality of the end product.  WillowFlex is consistently sized for a smooth printing experience. In addition, because it is flexible it is much easier to work with then standard hard filaments (much more forgiving!)

Is a heated build plate required in order to print with WillowFlex?

No, WillowFlex doesn’t need a heated bed to print.  You can print directly onto print tape, glue, etc. We have found that in general WillowFlex is very forgiving.  The most important is to follow our print settings recommendations and make sure that you have a good adhesion of the first layer.

Can WillowFlex be used with Support Material?

Yes.  We have printed WillowFlex with WillowFlex as the supporting material, and also with other support materials.  Both printed without problem, although because WillowFlex has such strong adhesive properties, the support material is not as easy to remove as with other filament types.

How is the finish of WillowFlex? Can it be improved?

As a natural material and elastomer, WillowFlex tends to have a very smooth finish. It has good bonding properties and so can also relatively easily be made watertight.

We have tried treating it with Acetone, but then it swells/expands, causing bubbles between the print outlines (outer shell swells, inner shell doesn’t) and ruining the nice outside finish of the print.

Does WillowFlex bond with ABS or PLA?

WillowFlex bonds very well with PLA. On our youtube channel you can find a printed example of a WillowFlex/ PLA-Hinge. We haven’t done as many tests with ABS, but it appears to react similarly.


Is WillowFlex safe to use with food?

At this time we don’t have a certification regarding using WillowFlex with food or drink. We have sent samples to be tested and hope to have results for you in the near future.

What we do know is that when the raw material breaks down completely there is no harmful residues left in the ground, or also when growing plants on the resulting soil. (More information about EU 13432 testing process). So we are pretty sure that the same is true around food as well.

Is WillowFlex heat/ cold/ water/ chemical resistant?


WillowFlex is able to maintain its structural integrity at temperatures in excess of 100° C. You can print your teacup and the boiling water won’t affecting the structure. You can leave your 3D printed sandals in the sun and they won’t deform when you step into them.  We are also excited for what this heat resistance will mean for electronic applications such as flexible PV Panels.


WillowFlex has been confirmed to retain its flexibility at – 15° C. Giving materials to children is a great way to test all the possible uses! Our first sample 3D Printed WillowFlex boxes were put in and out of our freezer for 3 months so that they could make their own ice cubes. Over the time we also created some custom ice-cube forms for them (Tux, the Linux Penguin – Flower – Heart – NEED LINKS). They continue to withstand the freezing and defrosting process and the flexible surface makes it easy to remove shaped ice cubes.


The ability of WillowFlex to remain unchanged when reacting with chemicals is still being tested. If you have a specific use you are interested in, please contact us directly: business@bioinspiration.eu

Can WillowFlex be Colored?

We have tested WillowFlex with different paints including ecological watercolor paint (Article). We have found that in total, WillowFlex is a very accepting material and that extends to color as well.

WillowFlex is already offered in 10 colors, and if you place an order for 15 kgs or more of filament, then we can also create a custom color for you based on a Pantone swatch. (Delivery in 1.5-2 months). Just contact us at orders@bioinspiration.eu.

Are there any safety concerns when using WillowFlex?

Generally no. WillowFlex (and almost all natural filaments) are much safer to work with then traditional chemical filaments.

That being said, we always recommend working in a room with ventilation because even natural materials can still give off micro-particles.

My Question has not been answered here, what can I do?

Just email us at info@bioinspiration.eu and one of our team-members will respond to your question as soon as possible.


Who is bringing us this filament?

WillowFlex is the first product of BioInspiration, a Berlin-Area company dedicated to expanding the Organic Material Evolution. BioInspiration expands access to materials and process that follow nature’s lead – compostable, upcyclable, harmless, innovative, resilient. We have a particular focus on decentralized production and the maker movement.

What are your main channels concerning updated-information related to WillowFlex and other new materials?

Like all good companies, you can get in touch with us in a variety of ways:
Newsletter: Signup at the bottom of the page
Phone: +49 03334 2995 293

I would like to resell WillowFlex or start a co-creation project with the team of BioInspiration. What is the next step?

Great – we would be happy to work with you.  We are always on the search for like minds that put quality and responsibility first.

You can which other Resellers have joined the Material Evolution here on our Resellers Page. Or you can get in touch with Steffen, steffen@bioinspiration.eu and we will get started with the process as soon as possible!