The customization that 3D printing makes possible is a natural fit for consumer goods like footwear, but the technology can also bring real sustainability benefits as well. Hilos shoes combine a custom 3D printed TPU platform with a leather upper for a luxury pair of shoes that are produced on demand and with little waste — even using less water than conventional shoe manufacturing. But the real key to these shoes is in their construction; an ancient fastening technique holds each pair of Hilos together for as long as the wearer owns them, and then makes it simple to recycle all the parts of the shoe when they return to the manufacturer. | This episode of The Cool Parts Show brought to you by Carpenter Additive

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Related Resources

• More on Hilos
• HP’s Multi Jet Fusion (MJF) process
• Other examples of 3D printed footwear: flip-flops, insoles
• Our reporting on sustainability

Transcript

Stephanie Hendrixson 

An ancient form of shoemaking meets modern 3D printing. On this episode of The Cool Parts Show, we'll learn what makes these shoes as sustainable as they are stylish.

Pete Zelinski 

The Cool Parts Show is brought to you by Carpenter Additive. When it comes to managing metal powder there is no one size fits all approach. Stick around after the episode to learn more.

Pete Zelinski 

I'm Pete

Stephanie Hendrixson 

I'm Stephanie.

Pete Zelinski 

Welcome to The Cool Parts Show.

Stephanie Hendrixson 

This is our show all about cool, unique, interesting, sometimes aesthetically pleasing 3D printed parts.

Pete Zelinski 

These are some stylish shoes. I feel as though we're going to do another footwear episode. I am down for that.

Stephanie Hendrixson 

We are going to do another footwear episode and if you want to see our past footwear episodes, you can find them at TheCoolPartsShow.com. But today, we are going to be talking about these shoes that were made by a new company called Hilos. They are specializing in these kind of fashionable heels. And they make these shoes with a combination of 3D printing and some actually really conventional, traditional shoe making techniques that we'll talk about later. But we're going to talk about these shoes not just because they are made on demand, custom to the person who orders them. But because they are really intentionally designed with circularity in mind. And when I say that I mean the circular economy, recapturing material, thinking about recycling and the end of this product's life. So these are a great example of customization and 3D printing and production, but they're also a really nice illustration of the circular economy and how it plays out for a consumer product.

Pete Zelinski 

That was a lot. Can I make an observation, they don't look 3D printed.

Stephanie Hendrixson 

They don't. And that's something I really like about these shoes. So the 3D printed part is this bottom portion, the platform. This is 3D printed TPU, and then they hydro dip it which is where you get this woodgrain from. The shoe itself is only a couple of materials. So there's that 3D printed platform, and then these leather pieces that form the upper, and maybe a couple of fasteners and that's really it. It's a pretty simple construction all put together.

Pete Zelinski 

So I love that. They weren't 3D printed for the sake of 3D printing and to look at the shoes, you wouldn't necessarily know how they were produced. You mentioned the circular economy. So how does 3D printing close that circle?

Stephanie Hendrixson 

So I think now would be a perfect time to introduce you to Gaia Giladi. She's one of the co-founders of Hilos and she's actually the person who designed this shoe. She can talk more about that.

Gaia Giladi 

Hilos was founded to end the overproduction and waste problem in the footwear industry. 24 billion shoes are made every year and one out of five of those go straight into the landfill. And that really happens because we're forced to predict what styles are going to sell. My co-founder and I envision a future where you don't have to do that anymore and you can actually make to each order. And so that's why our mission is to change the way that we make. So that nothing goes to waste and everything that we put in can be taken back. Circularity was ultimately our biggest inspiration when designing the Georgia and Grace styles. That really led us through the entire development process and that helped us kind of have a guiding star when designing.

Pete Zelinski 

Okay, So when you think about 3D printing as a way to conserve material, reduce waste, we usually think about that on a part level scale. With additive manufacturing, you are creating the object by adding material just where it's needed, instead of cutting the form out of a larger starting stock. And so in 3D printing, there's not that waste in the same sense as far as scrap material. Gaia is referring to conserving resources in a broader scale, because additive manufacturing's freedom to have tighter lead times and shorter production batches means she doesn't have to pre think what's going to be in style, doesn't have to pre think how well these new designs will be received. And she doesn't have to risk over producing and maybe throwing away a lot of shoes.

Stephanie Hendrixson 

Yeah, exactly. So Hilos keeps the leather in stock, they work with a supplier who does the 3D printing who has the TPU material in stock, but those two things don't come together and make a shoe until somebody goes online and orders them. And when you do buy a pair of shoes, you can buy them in whatever size you need. If you need two different sizes, or one foot wider than the other, you can make those adjustments. And because Hilos is not producing any excess, they don't have extra inventory that they might have to throw away later.

Pete Zelinski 

So these are made on demand. But as you said 3D printing is just part of it. So what else goes into making a shoe?

Stephanie Hendrixson 

So these shoes are pretty simple when you look at how shoes are typically manufactured. So just the sole alone, typically you'd have the outsole, the midsole, the insole, all these different layers of like rubber and fabric and foam that are getting glued together usually, and so you end With a lot of fasteners, there's a lot of assembly that's going on. What Hilos has done is consolidate that whole outsole, midsole, insole into just this one 3D printed platform. And so inside of here there's a lattice structure that takes the place of that foam and then everything is just consolidated into this one piece. And so all they need to do is join these two pieces together. And so the technique that they use is actually a really interesting technique called string lasting. I'll let Gaia explain what that is.

Gaia Giladi 

String lasting is an ancient form of shoemaking, where you essentially attach a leather upper to an insole using string, and then you glue that insole and leather upper to an outsole. We were really inspired by this assembly mechanism because we saw a way to do it without using glues, using geometries within CAD work and within additive manufacturing. And so we kind of reimagined it, and created those same channels that you use in string lasting within the platform that we use for our shoes. And so instead of gluing and layering those pieces together, we are able to slot the leather in to place within the platform using a cable which then allows us to easily disassemble the shoe and recycle each piece.

Pete Zelinski 

Okay, so the string lasting is important for the shoes disassembly, a replacement for glue. If you really want circular production, if you're serious and and deliberate about reclaiming material at the end of the product's life reusing the material, then your engineering of the product has to pre think disassembly.

Stephanie Hendrixson 

Disassembly Yeah, exactly. So when somebody is done with a pair of Hilos, they actually can mail them right back, they come with a return shipping label. And what the company can then do is if you look at the bottom of the shoe, there's this little hole here with the cable inside, which is visible. And so all they have to do is cut that cable, that releases the string lasting mechanism, you separate the leather and the TPU and both can go into different recycling streams. So the leather gets ground up, it gets turned into these sheets of recycled leather that you can use for furniture upholstery and other things like that. The TPU gets ground up and turned into injection molding pellets. So just because those materials are no longer part of a shoe, it doesn't mean they don't have value anymore. They're recapturing those resources, preserving the value and putting them into different streams.

Pete Zelinski 

Okay, the material you mentioned TPU, you've said that a couple times. TPU, flexible polymer, 3D printable polymer, not a material we necessarily associate with shoes, at least not fashionable shoes like this. Talk about that.

Stephanie Hendrixson 

Yeah, so TPU does get used in like athletic shoes and things like that, because of the way it flexes and it has like some gripping properties. It is definitely unusual to see it in a heel like this.

Pete Zelinski 

So the 3D printing process, deposition sintering. What?

Stephanie Hendrixson 

Multi Jet Fusion, so the process from HP that uses polymer powder.

Pete Zelinski 

3D printed with Multi Jet Fusion. We're familiar with that. We've done past episodes of the show on other products made through Multi Jet Fusion. I wonder if Hilos was familiar with it? Was was Gaia familiar with it? Did she come from a manufacturing place? Is she a manufacturer?

Stephanie Hendrixson 

So this is actually like my favorite part of the story? So the answer is no. Her co-founder had this idea to make custom shoes through 3D printing. He brought her on because she's a trained fashion designer, but her career up until this point was designing apparel, which is different than designing shoes. So the two of them were kind of working through this trying to figure out how to launch a footwear line. They brought on an engineer who knew CAD, who knew design but didn't really know 3D printing yet. And so the three of them together sort of worked all of this out. They had this great idea they knew or they thought at least that it was possible. And coming from a nonmanufacturing, outsider's perspective, it seemed that 3D printing was going to be the tool to get them there.

Pete Zelinski 

So they knew what they wanted to make and they had this vision for how they wanted to make it, particularly including reclaiming the product at the end of its life. They knew that 3D printing was a means to that end, but I guess that's all they knew. Where are they now? Are they are they manufacturers now? Are they going to be doing their own manufacturing?

Stephanie Hendrixson 

Right? So they're doing manufacturing in the sense that they're assembling the shoes in house right now. They have a supplier that's doing the 3D printing. But they are currently working on opening the Center of Excellence for Circular Footwear, which is going to be a facility where they do their own manufacturing but it's also going to be a space to collaborate with other footwear companies and other types of companies in general to help them make the same leap.

Gaia Giladi 

So the two main things to know about the Center of Excellence for Circular Footwear are that it's going to allow us to co-develop, to have a place for our partners and other brands to collaborate, and to meet and really scale what we're doing and showcase to the industry, what can be done in circular footwear and additive manufacturing. And then the second thing is to co-promote and really bring awareness to the industry and to the world of this new process. And like I said earlier, to really prove that you can make footwear, without over producing and without wasting. I think that the biggest lesson that we've learned is that you really need to own your own manufacturing process, if you want to see change happening and if you want to see innovation. It's really important to own that piece. You know, we learned early on that the industry is truly steeped in tradition and for us to bring our vision to life, we needed to invent it ourselves. And so it's been really important for us to be leaders in this space, and to really prove to the industry and the world that there is a way to make shoes that doesn't over produce and doesn't waste. And it can look good, be aesthetically pleasing, be commercial, and sustainably and ethically produced.

Pete Zelinski 

Alright, so they're preparing to become their own manufacturer, they're preparing to help other footwear makers produce this way. So what's next for Hilos?

Stephanie Hendrixson 

So you notice right away that these shoes don't look 3D printed and that's actually really intentional. Gaia thought it was important for this very first product to be something that looks really accessible, something that you could picture yourself wearing or a friend wearing. But that's not going to be the case forever. I think Hilos and some other consumer facing companies that are using 3D printing have realized that 3D printing allows you to make these really crazy, chaotic looking designs, and that's not necessarily super appealing to a customer right off the bat. I think people are going to need time to kind of get used to the idea of 3D printing. And so, for Hilos right now, they're really just focused on the customization and the comfort of these shoes, because that's going to let them acquire customers and in the future allow them to do those those crazy innovative designs because people will be sort of used to the idea.

Pete Zelinski 

Yeah, so 3D printing can do weird, but it doesn't have to do weird. And with some products, the right starting point is to let 3D printing produce the product you expect, use that as the foundation, the platform to begin elaborating from there exploring more of the design possibilities that 3D printing brings.

Stephanie Hendrixson 

Yeah, start with the product that you expect. And I think that is sort of the idea behind the way that this shoe looks. But I will say it is a different shoe in the way that it fits in the way that it feels. So I am not a person who wears heels a lot or really at all. But when I got these shoes, I pulled them out of the box and I tried them on. And right out of the box, they feel sort of heavy and like you might think that they would be sort of clunky on your feet, but actually the way they're designed and the result of that TPU material just makes them really stable and really comfortable. So if Hilos' goal is to get into the marketplace with a shoe that is functional and comfortable as a way to getting to those more innovative designs, coming from material he'll skeptic Yeah, I think they're succeeding.

Pete Zelinski 

Alright, let me try to wrap this up. 3D printed footwear made by Hilos. The base is made through Multi Jet Fusion. And the base consolidates into one piece a lot of elements that would otherwise be separate components glued together in a more conventional shoe. The creators had a vision of a circular economy approach to production. Not only interested in getting the shoe to the consumer, the wearer, but also getting the shoe back at the end of its life so that they can reclaim the material, reuse it, control waste as much as possible. 3D printing controls waste in another sense as well because not only does the additive process control how much material goes into this foundational element of the shoe, but it also allows Hilos to manufacture on demand and therefore eliminate any need for inventory for trying to predict how many sales there would be, potentially predict wrong, potentially waste by over producing. Again, the shoes were made with a circular economy mode of production in mind and that aim drove design from the beginning it drove the choice of 3D printing. But it drove other design choices too. Including the way that this leather upper is assembled. It is held on using string lasting using a very old method of assembling shoes. But that choice allows for easy disassembly. When the wearer is done with these shoes and uses the mailing label that came with them to return the shoes to Hilos, they can be taken apart, and all of these different components of the shoe can be reclaimed, reused.

Stephanie Hendrixson 

Yeah, I think that covers it. There was a lot.

Pete Zelinski 

That was a lot. There's a lot to say. Stephanie, you've written about Hilos, you've written about these shoes that they've designed. Where can people find your article?

Stephanie Hendrixson 

You can find the article at AdditiveManufacturing.media, just search for Hilos.

Pete Zelinski 

Stephanie has actually done a lot of writing and reporting about the intersection between additive manufacturing and the circular economy. So in the show’s description, we'll include links to lots of stuff.

Stephanie Hendrixson 

Alright, if you liked the show, we hope you'll subscribe. Leave us a like, leave us a comment. If you have a cool part you'd like to see featured, email us at CoolParts@AdditiveManufacturing.media. Thanks for watching.

Pete Zelinski 

This episode is brought to you by Carpenter Additive, we're past the point of not knowing how to qualify metal 3D printed parts. We know, it's just that different end users of those parts have different qualification requirements. Additive manufacturing service providers have to navigate that and Carpenter Additive has to think about that in tailoring powder management solutions.

William Herbert 

Our customers typically will have, if they are a service provider, they will have a series of end user customers who may be say OEMs in the aerospace world. And each of them has a fairly large team of engineers who have been doing this for decades or more, and have developed all these standards, regulations, paperwork. So it is certainly a challenge to thread the needle between all of these different requirements. We start really high level, we walk on the shop floor, we asked them about their source to sink, how do you bring in the materials, goods in. You know, send that material to each of the systems. And then what we're really interested is how do they reuse that material. So what we do is called the Value Stream Map. Pretty often that leads to a series of things that were either overlooked or hadn't really boiled up to the surface yet in terms of potential risks, or potential challenges or inefficiencies that exist. A lot of the customers we work with, especially in the more regulated industries, such as space or medical or aerospace, have already been through those early learning stages. They've put five plus years into this. They've done the product design and the design for the additive manufacturing and now they're starting to reach some of the more finicky problems that you get when you're at the scale of maybe 5 to 10 machines. You're running different materials simultaneously, you're doing different programs. We get to take the best from the medical field and the aerospace field. We understand the specifications and the standards that exist in each of those fields and we can sort of take the best elements of those and customize that to our customers.