Mobility is a basic human need, yet millions of amputees struggle to access prosthetics due to high costs, long manufacturing rates, and a lack of customization. Even basic prosthetic limbs cost thousands of dollars, with models in the U.S. ranging from $5,000 to $7,000, while advanced versions exceed $10,000. The situation is worse in developing countries like the Philippines, where up to 90% of amputees cannot afford prosthetics, leaving many to makeshift solutions like using crutches or sticks their whole lives. Furthermore, the overly high cost of these prosthetic limbs leads to a lower demand- since they are way too expensive for people to afford! The lack of demand leads to less manufacturing, and therefore the rate of professional prosthetists declines. 

Beyond mobility challenges, these barriers affect amputees' psychological and social well-being. In underserved regions, prosthetic wait times stretch for months. This is due to prosthetics' high precision in manufacturing, since each person's residual limb is so unique. Thus mass-produced limbs often fit poorly, causing discomfort and long-term health issues. Despite advancements in prosthetic technology, affordability and accessibility remain major obstacles.

3D printing offers a promising solution. Unlike traditional manufacturing, which is expensive and time-consuming, 3D printing can produce prosthetics for under $300 in as little as 24 hours. This technology enables precise customization using 3D scans, ensuring a better fit. 

Additionally, 3D printing supports decentralized production, making it possible to manufacture prosthetics locally in remote areas, cutting down on logistical costs and delays. Organizations like e-NABLE have already demonstrated the potential of 3D-printed prosthetics, specifically hands, delivering low-cost, customized limbs to those in need. The ability to quickly refine and update designs ensures users receive the most effective solutions.

By making prosthetics more affordable, accessible, and personalized, 3D printing has the potential to revolutionize mobility for amputees worldwide. This innovation could help millions regain independence and improve their quality of life, addressing a long-standing global need.

 

Materials Used:

3D Printing Materials & Tools: 

• PLA Filament

• Custom built FDM Printer

• Nozzle (0.6mm)

• Fiberglass infused Nylon filament

• Sandpaper
• Measuring tape
• 3D Scanner (Creality K1)

Design & Modeling: 

• Fusion 360 Software
• PrusaSlicer Software
• Meshmixer 

Safety during testing: 

• Support chair for client safety
• Socket liner for limb protection

Sketching the general Prosthetic 

The initial design process began with sketches on paper, incorporating insight gained from discussions with Dr. Knight, including topics such as prosthetic biomechanics, material efficiency, and weight distribution. The photographs below contain originial sketches and notes relevant to this step.

 

Prototype Development & Printing Section 1 (Foot)

Before printing a full-scale prosthetic, I created scaled-down prototypes to test structural integrity and weight distribution. I broke down the full prosthetic into three sections, including the socket, shaft and foot. I started off with the foot, since I did not have scans yet to compete the other two sections; two different foot designs were tested:

1. A cholla plant-inspired lattice structure for enhanced strength, flexibility and material efficiency

2. A traditional solid foot design for comparison

Below are some original sketches and 3D models of the foot designs: 

 

These foot sketches I made were converted into 3D models using Fusion 360, including mainly the sketch and extrude functions. The designs were made in Fusion 360, but I used PrusaSlicer to add support structures and optimized layer settings- this part done with the help of Mr. Simon, our school's Design Specialist. The scaled models were printed using PLA filament, and stress tests were performed to analyze durability. Below are photographs of the printed prototypes (green prototype is cholla inspired and white is traditional):

I liked the cholla plant-inspired lattice structure better, mainly because it required less support beams while printing, meaning I had to do very little sanding for the final product. If you look closely at the pictures above, the support beams were more difficult to remove, causing a lot of bumps and therefore more sanding. Furthermore, the cholla inspired design was more material efficient, as it required less material to print than the traditional solid foot design, even though it appeared to be “bigger” in size. Some improvements for the final design is to include more triangles; there were weak points in the non-triangular blob/hole part. I will fix that, and obviously clean up the overall design as well. According to my research, cholla plants are a great natural structure to inspire any design by, especially prosthetics. Generally, I am aiming to reduce the amount of material use, while maintaining durability and flexibility. The cholla plant has been designed to meet these exact requirements, which is why I particularly chose to try a prosthetic design based on this plant. Overall, it looks like the cholla plant-inspired lattice structure is the better choice.

 

Scanning & Measurement Collection

Since my client was located in South Africa, remote scanning was required. I had planned for this stage to be the second step, however circumstances caused this to be one of the last ones. 

Initially, I experimented with mobile scanning apps like Zephyr but found the resolution insufficient for accurate prosthetic modeling, as seen by the messy scans in the pictures below: 

Dr. Riaan Knight, the prosthetist whom I had been seeking advice from for this project, offered to try doing the scan himself with the client in South Africa. He attempted to use an app on the iphone 16 to capture precise limb measurements; unfortunately that did not work very well either. Finding a way to get the scans caused a huge delay on this project, to the point that by the time I had reached South Africa to meet the client, I was still on the scanning stage when I was meant to be on the product testing phase! Luckily Mr. Sheldon, a 3D lab owner, was willing to scan my clients stump during the holiday break. He used a (scanner type), which was a high level scanner intended for precision based projects- just like mine! The scan files (STL format) were cleaned up using meshmixer and sent to me, allowing me to import the scans into Fusion 360. Below are some photographs of Mr.Sheldon's lab, the scanning process and scan results:

 

 

Prototype Development & Printing Section 2 (Socket and Shaft)

As soon as I received the scans, I developed the socket and shaft the same day. While I had accurate scans that could provide measurements for the overall prosthetic, I decided to also have the manual measurements available to me; thus I got a hold of my clients manual measurements from Dr. Riaan Knight too. Here is a photograph of these measurements below:

 

 

I made a shaft, and then attached the socket to it. I included the cholla plant inspired lattice structure, particularly to the shaft by including pipe-like structures to attach/support the socket. I did this primarily using the sketch and pipe tools on Fusion 360. Then, I printed out my first full prosthetic prototype. Below are photographs of the 3D model and prototype of the first version:

 

A strength test was then conducted; the breaking points are circled in photographs below: 

As you can see, there were a few breaking points I needed to address; however, Mr. Sheldon mentioned that the design was actually quite strong, and it took him a lot of effort to break it. He advised me to taper the pipes to the socket and shaft connections, as that would reduce static stress and therefore increase the durability of the design. I also needed to make the leg shorter, because with all honesty I was super silly and decided to make the first prototype with no regard to proper measurements (this was prior to asking Dr. Riaan Knight for the clients manual measurements). Anywho, I made some changes to my design, this time following the proper measurements along with adding tapering with the use of the chamfer tool on Fusion 360. Below are photographs of how I included tapering, as well as the new prototype and 3D model. 

 

This one was much stronger, the tapering really helped, since it balanced out the static stress. It took much more effort to break this one. I decided that this design was the prototype to go full scale with. The photo of it's strength test is below: 

 

Full-Scale Printing & Assembly

Once the design was finalized, I proceeded with a single-piece print for structural integrity. The socket and shaft were printed with a custom built FDM printer with a 0.6mm nozzle; the material I used was a nylon, specifically Fiberglass infused Nylon filament.

Unfortunately, the printer came across an error during the printing process and caused the first full scale prosthetic to be a complete failure. See below for a photograph of this. 

 

Luckily, there was no problem with my design itself, so I was able to print it again as soon as the printer was fixed- which happened within a few days. Thankfully the print was successful the second time; after printing, the prosthetic underwent some sanding, and it was then good to go for testing! Photographs of the final print are below:

 

Testing & Evaluation

The final prosthetic was tested based on the evaluation of success criteria, presented in detail located in the Analysis section under Table #1.

Generally speaking however, testing included:

• Functionality: The client attempted standing, balance adjustments, and walking (though swelling prevented a full test).
• Comfort: Feedback was collected on socket fit and material friction.
• Durability: Weight testing exceeded 100 kg with no structural failure.
• Cost-Effectiveness: The total production cost was analyzed against traditional prosthetics.
• User Satisfaction: A structured interview was conducted with the client, Dr. Knight, and Mr. Sheldon to assess overall impressions. 

Below are some relevant pictures during testing:

And here are some special notes from Dr. Riaan Knight and Mr. Sheldon. For context, Dr. Riaan Knight sent his message after the testing session. Mr. Sheldons messages reflect the complexity of my project to the point where he was afraid he could not help me, but subsequently becoming supportive when I explained the proccess and my knowledge in our meeting. 

 

Evaluation of Product based on Success Criteria 

Table #1: Evaluation of Success Criteria for 3D Printing a Below Knee Prosthetic Limb

The 3D-printed prosthetic successfully supported the client’s weight, demonstrating excellent durability by withstanding over 100 kg without structural failure. Additionally, it only costs 200$, which is approximately 1/15th of the price of traditional prosthetics, making it a highly affordable alternative. The design was also significantly lighter, weighing just 1 kg compared to the 1.5–2.0 kg average of conventional models. However, friction within the socket caused discomfort, suggesting the need for material improvements such as smoother coatings or multi-material embedding. While full functional testing was limited due to external factors, the results indicate that 3D printing offers a promising, cost-effective, and customizable approach to prosthetic development; as Dr. Riaan Knight, a certified prosthetist, put it, my work has “made the pavement for 3D prosthetics”, further proving its potential impact.

PDF of bibliography is linked under "attachments" 

Ms. Willoughy - Mentor/Advisor

Mr. Simon - School Design Specialist

 

Special thanks to the following people for making extra time for my project regardless of busy schedules: 

Dr. Riaan Knight - Prosthetist + Clinic Owner

Mr. Sheldon - Design Specialist + 3D Lab Owner 

My Aunt - Amputee/client 

 

I am most especially thankful to my Mother and Father, who supported me throughout this entire project regardless of the many inconviences and expenses I caused! I am truly greatfull to have such parents.