Getting to know... macu4: 3D Printed Arm Prosthetics!

September 7th, 2022 by ShapeDiver

Learn how this Swiss startup is using Parametric Design and 3D Printing to radically transform how arm prosthetics are made.

Check out their configurator!

One of the many advantages of Additive Manufacturing (3D Printing) is its relatively short production times compared to traditional manufacturing methods such as casting. In this interview, you'll meet the team behind macu4. They are leveraging this advantage to transform the way arm prosthetics are manufactured.

They saw that traditional offerings were not only heavy to wear and expensive, but the whole process took too much time, and they took action.

They knew they could shorten the entire process by using parametric design to customize each patient's forearm easily and then 3D printing to manufacture each part. The only missing link was finding a solution that could allow them to host their Grasshopper file on their website and output the right production file for every patient. How did they solve it? Read along to find out!

1. Hello there! Please give us a background on your team:

We are an entrepreneurial team of 3 co-founders. Myriam holds a Ph.D. in Epidemiology and started in 2006 to work in the field of orthopedic devices. Lukas and Alec will finalize their Masters in Medical Engineering in 2022 and have already designed different assistive devices and created parametric models.

We love thinking outside the box to make low-tech smart, whether it is Myriam's business model or Lukas and Alec's manufacturing and design approaches. What fascinates us about our job is the smile on the face of our end users and the happy messages they send us.

What drives us is the belief that we can contribute to inspiring the care path for assistive devices. Getting started in this field takes courage, perseverance, and the right way to deal with negative feedback from traditional stakeholders who do not think out of the box.


2. What sparked this idea?

There are more than 20 million people worldwide with missing limbs. The majority is not using any device. Many because of the high costs, others because of lacking comfort or functions.

For families with affected children, it's challenging because they grow and frequently need a new customized prosthesis element. But only a few countries have a substantial reimbursement for such devices; therefore, the cost is a fundamental limitation.

At the same time, people have trouble getting used to the weight of an artificial limb or the sweating inside the device. Even though arm prosthetics have become more versatile, today's state of the art does not manage to solve these user pains sufficiently.


3. What's the main problem or reason for macu4 to exist?

From the user perspective, we quickly realized that significant changes wouldn't happen at the required pace since forearm prosthetics is a very niche market. Niche markets are not attractive enough for established players and are too risky for investors when it is about low-tech. But making low-tech smart is the way to go, and besides that as well quite exciting.

"Smart" does not mean changing only the design or the material. It refers to the entire value chain: how end users can access it, how much it costs, how to interact with the user, how to collect measurement data, how to manufacture it, etc.

We decided that we would solve the problem by combining new technologies such as additive manufacturing and parametric models with new business models to create new possibilities with the overarching goal of improving the quality of life of people that look for an arm prosthesis.


4. What's the status quo? How are you changing this?

The customization process of an arm socket (in a traditional way) looks like this:

(1) The patient has to travel to the prosthetist (in larger cities, there is no problem, but in smaller cities or villages, there is a need to travel to the prosthetist). 

(2) The prosthetist has to examine the arm stump and make a plaster cast. Some shaft technologies cannot work well with a scan because scanning is complex. In the case of arm stumps and the traditional liner (inner part of a shaft) has to sit perfectly on the arm. 

(3) The prosthetist produces in a time-consuming process the first test component. A few cases can now consider a 3D silicon print of such parts, as this would save time. 

(4) The prosthetic arm is finalized. 

(5) The patient travels again to the prosthetist to test the first version of the prosthetic arm. 

(6) If needed, the prosthetist has to rework the shaft/inlet. 

(7) The patient travels again to the prosthetist to receive the final prosthetic arm.

At macu4, we created a new approach that saves time while customizing the socket.

The first key element is the measurement, which can be done manually, photo-based, or with a scan - measurements are extracted by an algorithm. The configuration equals selecting the colors and additional modules a user requires. The second key element is the socket customization which is done by the parametric model and based on the measurement data - in this step and during the measurement, there are considerable reductions in time.

5. What have been the main challenges in making this happen?

We bundle several aspects currently neglected by the market into one approach. For example:

1. We introduce a simplified measurement technique and are therefore able to offer our solution as well via a B2C model.

2. We use 3D printing to outsource the manufacturing of a customized device and overcome current design limitations.

3. We automate the customization process with the parametric model approach and dramatically cut costs.

We do all this within an industry with heavily rigid structures. The biggest challenge during the development process was and is the fundraising and the relationship building with prosthetists. 

For investors, the approach covers too many new elements. For prosthetists, it is difficult to think out of the box and see the long-term opportunities of the Macu4 approach (i.e., serve more clients simultaneously or offer people with out-of-pocket payments a much cheaper solution).

6. How is Parametric Design (Grasshopper) involved?

We were looking for a way to lower the costs of customized prosthetics because the working steps to customize a prosthesis socket are highly time-consuming. At the same time, we were looking for a possibility to introduce remote measurement for users.

The best way to approach this was to create the prosthetic socket design as a parametric model. A third requirement was that the prosthetist should get access to the socket design through our webshop and without the need for expert skills or subscription to expert software. The combination of Grasshopper and ShapeDiver fulfilled all of those requirements.

7. What are the benefits of using 3D printing vs. the traditional approach?

The designs developed by macu4 are always produced by 3D printing. Both the customized and the standard parts. We decided to make these designs by 3D printing because this is the way to go for customizations. But it also helps to overcome current design weaknesses of existing product offerings in the market, i.e., to make parts lighter.


Another significant advantage of 3D printing is outsourcing the production efficiently (and decentralizing it) and running several tests during the design development phases without high initial investment in materials. This way, the cost burden is relatively low for a startup that has only limited resources at the beginning.

8. Which other companies are involved in this project?

The value chain starts with finalizing the STL files for the required product designs. Especially the files of customized designs are created just in time. For this process and the visualization of the 3D model, we work with ShapeDiver. Before the designs are 3D printed, we mark them digitally to make them identifiable once they are provided to the clients. For this step, we partially use the software solution of Additive Marking GmbH.


9. How is ShapeDiver helping you?

ShapeDiver is the online platform that processes the Grasshopper file for running the socket model. Thus, we can focus on the core technology of macu4, the parametric approach itself, and the customer frontend in which we embed the ShapeDiver viewer. 

For macu4, the software solution is more than a software element. It is a comprehensive service. We go from reliable 3D visualizations to custom-made consultancy services to get access to a broader software development network. 


10. Can you describe the complete process for a user to get their prosthesis done via Macu4?

We sell our design solutions directly to professionals (B2B) and end-users (B2C). The process with end-users is as follows:

A person with a missing forearm and a specific bi-manual activity in mind, for example, cycling or kayaking, finds us online via social media, search engines, or recommendations via 3rd parties. On our website, the user has the option to either contact us directly or get initially informed by our explanatory videos and our FAQ.

1. Once the person feels that the Macu4 Explorer could be a suitable solution for them, the self-measurement takes place. Self-measurement means that the user follows clear instructions on providing the Macu4 support team with data on their arm. It is a method where the user prints a template on paper and takes three photos of their arm. Macu4 processes the images and extracts the measurement values we need for the parametric shaft model.

2. When this is done, we inform the user by email to create an account in our online configurator and start the configuration. If desired, a video call takes place before the configuration. For the activity modules, a user always configures the required size alone and based on two measurement values that we provide. For the customized shaft, the user only receives a measurement code. As a final step, the user confirms the configuration(s) and pays online.

3. Once this is done, we finalize the shaft configuration based on the measurements we extracted from the photos and start the 3D printing process.

4. Finally, we assemble and label the product. The user receives the products by mail, and we conduct a video call to ensure that the user gets all parts and solves any questions they might have.


11. What's the long-term for macu4?

Our clients are of different age groups. They are either already using a prosthesis or not. What they have in common is that they look for a lightweight device that is modular and suitable for sports.

For some, it is the add-on product; for others, it is the first-choice solution. Our goal is to successfully launch the Macu4 approach, introduce end-users to the parametric model-based configurations of their devices and contribute to people's well-being.

- Thank you very much for your time today! We're delighted to have you as users on our platform!

Thank you as well for letting us tell our story here. We really appreciate it!

That's it for this new edition of Getting to know... Don't forget to visit macu4's website and follow them on their Instagram and LinkedIn accounts.

Would you like to get featured in this space? Send us an email at and tell us about your project or brand! We'd love to start a conversation.

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