We have known for some time that 3D printing products saves money for household goods (thing toys for Christmas for pennies on the dollar) and is good for the environment . There has even been some evidence that distributed manufacturing with 3D printing of assistive technology shows potential. The thinking is: If the devices are open source they offer accessible, affordable, and customizable solutions for the poor all over the world. Their real-world adoption, however, depends not only on the availability of openly shared designs, but also on their replicability when fabricated in different local contexts. To probe this idea, a new study investigates the replicability of open-source 3D printed two-piece open-source forearm crutch

Making a 3D Printed Crutch and Safety Testing

In the study replicability was considered from early-stage design and evaluated by introducing controlled variations from distributed manufacturing including the material feedstock, manufacturing equipment (type of 3D printer), and fabrication strategies. Four batches of crutches were printed and assembled using virgin and recycled filaments on small- and large-format 3D printers. After visual inspection, mechanical static load testing was performed following the main standard. Finally they determined if you could actually replicate them and they ran the economics.

The Results of Safety Testing a 3D Printed Crutch

The 3D printed crutches were strong. They had comparable mean load-bearing and consistent failure at extreme weights across batches, supporting the replicability of the design with 3D printing. It did not matter what printer and what filament as long as the basic guidelines were followed it worked.

The economic analysis showed the 3D printed crutch would run a maker $16.50-20.00, with the variations mostly due to the material feedstock, hence supporting the replication of the same design without significant cost variation. The scientists found that the open source crutches are a suitable option for fabricating accessible and affordable mobility aid products in low-resource settings anywhere in the world. Beyond this case study, they think the replicability of other open-source hardware for assistive devices needs to be considered as an early-stage design constraint. What this means is that when engineers are trying to design open hardware for everyone they allow for variability from local contexts and including product-specific quantitative approaches to assess replicability. Their hope is that this design shift can support accessibility and real-world applications of open-source assistive technology to the poorest in the world. A full open access version of the designs can be found here .