Joshua Pearce explains the use of open-source hardware to use recyclables as feedstock for custom 3D-printed products
WE ALL want to do good by the environment and recycle, but we will really recycle if we can make real money. In North America, most of us recycle metal because we are paid to bring in cans to our local grocery stores. Our country roads used to be littered with junked cars – no more. Those dead iron beasts are worth cold cash. Overall metal recycling has been a huge success. Sadly, there was not a good economic incentive in place for recycling plastic. So collectively, we have been terrible at it – only 9% of plastic has been recycled and the rest goes to landfills and/or pollutes the environment. Until now.
Several open-source technologies have matured that allow us to use 3D printers in our own homes to recycle waste plastic into valuable products. This approach is called “distributed recycling and additive manufacturing”, or DRAM for short, and can save you real money. It allows you to make custom products for less than the sales tax in the US (6%) on conventional consumer products ranging from skateboards and toys to syringe pumps and arthritis aids. How is this possible? The secret is the open-source ethos that is the foundation of the internet (see boxout). Millions of products you buy every day can be made from the contents of your recycling bin.
“Free” and “open source” refers to the source code of computer programs. It is made freely available for anyone to change and share – while at the same time being licensed with a viral licence that demands that if you modify the code you need to share your improvements with the same licence. Open-source hardware is the same idea with physical things. Open hardware has the design made free and publicly available so that anyone can study, modify, distribute, make, and sell the design or hardware based on that design. You can do anything you want with it as long as you share back to the community. The hardware’s source, the design from which it is made, is available in a format for making changes to it. For 3D-printable designs this normally includes the CAD file so you can modify it, along with the STL file so you can print it on most 3D printers. Ideally, open-source hardware uses readily-available components and materials, standard processes, open infrastructure, unrestricted content, and open-source design tools to maximise the ability of anyone to make and use it. Open source gives people the freedom to control their technology while sharing knowledge and encouraging commerce through the open exchange of designs. There are now many millions of these free designs circulating the web.
The DRAM method starts with waste plastic that we all produce every day from packaging to broken toys (see Figure 1). You wash it off with soap and water, or even run it through the dishwasher. Next, the plastic needs to be ground up into particles. If you are doing a lot of it, there are free plans for an industrial open source waste plastic granulator1 or if you are only doing a little bit, an office cross cut paper/CD shredder works just fine.
Next you have some choices. First, you can convert the particles into 3D-printing filament using a recyclebot (waste plastic extruder). Recyclebots themselves can have many of their components 3D printed from waste plastic (free designs are available at www.appropedia.org/recyclebot). Filament made with a recyclebot costs less than US$0.1/kg, whereas commercial filament costs US$24/kg or more.
The filament can then be used in a wide range of low-cost 3D printers (some as cheap as US$250) using fused filament fabrication (FFF). This is interesting because one of my earlier studies showed consumers could earn a return on investment of over 100% over 5 years by printing only one product per week after purchasing a US$1,250 3D printer using US$24/kg filament. You can do this by selecting products from free catalogues of open-source designs like YouMagine and MyMiniFactory. Recycled filament enables even higher return on investments (ROIs). For example, using a vertical recyclebot e-waste ABS makes it possible to print over 300 products (eg camera lens hoods) for the same price as those on Amazon.
The second approach is newer: you can skip the step of making filament and use fused particle fabrication (FPF) to directly 3D-print waste plastic into products. This approach is most amenable to large products on larger printers like the commercial cubic meter open source GigabotX (see Figure 2). The ROIs for small companies or “fab labs” making custom products even one at a time this way is substantial. That said, researchers at the University of Lorraine, France, developed an open-source desktop style FPF system that can print recycled shredded plastic for a few hundred dollars. Finally, if you need to make many of the same thing you can 3D-print moulds from recycled waste of a high temperature plastic like polycarbonate using any of the other processes and then either inject or extrude lower melting plastics into it.
My research group, along with dozens of labs and companies throughout the world have developed a wide array of open-source products that enable DRAM, including shredders, recyclebots, and both fused filament and fused particle 3D printers. These devices have been shown to work not only with the two most popular 3D printing plastics ABS (Lego blocks) and PLA (some McDonald’s cups) but also a long list of thermopolymers that you use every day including HDPE (milk jugs), PP (Rubbermaid and Sterilite products), and many more including LLDPE, PC, PETG, PS, composites with waste wood and even flexible TPUs. Most recently, my team and industry partner re:3D even found a way to directly print PET from shredded water bottles2 (see Figure 3) into products like face shields for the Covid-19 pandemic. PET has been historically tricky to work with and an extra drying stage is needed to keep the polymer from breaking down. Now it is possible to convert any plastic waste with a recycling symbol on it to valuable products yourself.
Consumers can fabricate plastic products for a fraction of the cost of commercial products, providing a very strong economic incentive for use of DRAM. There are already millions of free- and open-source 3D-printable designs for products, and “prosumers” (producing consumers) are already 3D printing products, saving themselves big money. For example, a study3 found that MyMiniFactory’s users saved over US$4m in one month alone just on a few toys. 3D printer filament is already listed on Amazon Basics along with other “everyday items”.
This indicates that distributed manufacturing with a polymer-based 3D printer is becoming mainstream. FFF plastic 3D printers are now reasonably mature, but FGF and recyclebot technology is roughly 10 years behind. Most families do not have an in-home 3D printer (even though their costs now make them quite accessible), let alone a reyclebot or GigabotX.
For larger systems, for DRAM to be a path to the circular economy these tools could be housed at neighbourhood-level enterprises like small local businesses, makerspaces, fablabs, or even schools.
This approach to recycling and manufacturing is better for the environment, and profitable to users both for making their own products, but also as small- and medium-sized businesses. DRAM may be the path to a circular economy but it will not be able to solve the plastics problem until it scales up. We need businesses to scale up production of recyclebots and direct extrusion machines in the same way that filament 3D printers are now a common sight in many businesses, most schools and a rapidly-growing number of homes. The global additive manufacturing market is expected to grow to US$36.61bn/y by 20274. The materials fraction of this is expected to reach about US$10bn. Yet, the global commodity plastics market is expected to reach a staggering US$686bn by 20265. These estimates, however, are based on status quo assumptions with no financial incentive for consumers to recycle plastic. We know the incentive exists, but consumers need educating about the potential of DRAM to become prosumers. Companies that encourage sharing open-source designs help stimulate this market and can benefit in several ways for aggressively sharing designs (see boxout), which makes DRAM even more valuable. Companies can also directly benefit from the billions of dollars of new market to support DRAM.
Downloading free designs and making valuable products from your waste plastic is cool, but it’s even cooler to share your own designs freely online, because:
1. There is the potential for massive peer review. For example, have you ever had a cool idea for a new technology out of your field and wondered if it could be brought to life, but didn’t have the money or time to bring on an engineering firm to have a go at it? Now you can. By sharing your idea online with an open-source licence, it can go all the way to detailed technical discussions of your new technology designs by fellow trained engineers – for free. Feedback can improve your skills, projects or products.
2. You are gaining visibility for your interests and passions, which could lead to you getting a job! Open source has helped my engineering students get jobs because employers can see for themselves what the students can actually do. It is quite common now for software programmers to advertise their skills by helping on open-source software projects, and engineers to show off their CAD talents on open-source 3D printing repos. This can be also be useful for recruiting collaborators, customers and even employees.
3. By providing high-quality documentation for your creations, they can also be used as educational aides so that those training in your field can learn “your way” of doing things. Thus, future collaborators or employees can be trained using your techniques. The most successful open-source projects are those that become a platform. They provide a base that others can use to build upon – often in unexpected ways.
I have been applying the open source-approach to my own lab equipment since I wrote the Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs6. For example, one of the most used tools from my lab is a customisable open source syringe pump7 (see Figure 4). We made a pump library using open-source and freely available OpenSCAD8, which is a script-based, parametric computer-aided design package enabling anyone to customise designs for themselves. The majority of the pump parts can be 3D printed and combined with readily available parts such as a stepper motor and steel rods. The pumps can be used as wireless control devices attached to an open-source Raspberry Pi computer (middle image Figure 4). Thus, you can control the pumps from any internet-connected device like a laptop or smartphone for almost any application where you need a syringe pump, from automated fluid handling to electrospinning. We found that the performance of the syringe pumps generated by the open-source library was of equivalent or better quality than commercial syringe pumps.
The cost to purchase a traditionally-manufactured syringe pump is US$260–1,509 for a single pump and US$1,800–2,606 for a dual pump (like the left and centre images). The cost of virgin materials for an open-source syringe pump is US$97 and US$154 for the single and double pump. As at the start of 2021, the designs for the open-source pump had been downloaded from two digital repositories over 10,000 times. This potentially equates to savings from more than US$1.6m (single pump) to more than US$25.9m (double pump). The value actually increases far more when considering the additional secondary benefits of enhanced research, derivations such as the Y-struder9 (right image Figure 4) that allows for material testing for additive manufacturing, enhanced education (for students that can now afford to use a syringe pump) and any secondary values from improved medical care when the pump is used. The ROI based on the cost to develop it is over 5,000% at the minimum. If virgin materials are replaced with recycled materials using the DRAM approach, the numbers become more insane because now the costs of the printed parts drop from US$9.25 (or about 16% of the total cost) down to US$0.03. With recycled plastic from DRAM, the more that is printed, the higher the savings.
A 2020 review10 found free- and open-source scientific hardware saved 87% compared to proprietary tools, and over 94% if both open source electronics and 3D printing were used. Savings of over 99% were found for sensors, reactors, analytical equipment and digital manufacturing equipment (eg laser sintering additive manufacturing system or an autosampler). All of these values go above 99% when a significant amount of 3D printing is used with recycled plastic.
When you share something in the global commons, you are planting a seed. Others may help that seed grow into a mighty tree – perhaps beyond your wildest ideas in value. Through a modest effort on my part to share the designs for something I had already made for myself, I helped out others. I know my own research has benefited to a tremendous extent from other researchers building upon what I have shared for free. What will you share?
1. Open Source Waste Plastic Granulator (2019); https://bit.ly/2VpsIRD
2. Towards Distributed Recycling with Additive Manufacturing of PET Flake Feedstocks (2020); https://bit.ly/3nepuMc
3. Impact of DIY Home Manufacturing with 3D Printing on the Toy and Game Market (2017); https://bit.ly/3A6MaBC
4. Additive Manufacturing Market to 2027 - Global Analysis and Forecasts by Material; Technology; and End-User (2019); https://bit.ly/2YrENa3
5. Commodity Plastic Market To Reach US$668.26bn by 2026 (2019); https://bit.ly/38SbZcK
6. Open-Source Lab, 1st Edition: How to Build Your Own Hardware and Reduce Research Costs (2013); https://bit.ly/2X300qk
7. Open-Source Syringe Pump Library (2014); https://bit.ly/3zQeSGW
9. Ystruder: Open Source Multifunction Extruder with Sensing and Monitoring Capabilities (2019); https://bit.ly/2YEfQII
10. Economic Savings for Scientific Free and Open Source Technology: A review (2020); https://bit.ly/3yUYMdG
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