I know this is a long shot, but I was looking through some of my old files and found a project I was working on a few years back. I am a board certified pediatric prosthetist and orthotist (no longer practicing). A few years back I was working on creating a FREE printable clubfoot orthosis, but never finished it because 1) We ended up having kids and I ran out of time, 2) I simply don't have the skills.
Infant with Clubfoot
Clubfoot is a very treatable musculoskeletal condition of no know cause. If left untreated it usually leaves kids unable to walk corrcetly and requiring a very invasive surgery that has poor results. Here is a primer on clubfoot if you are interested. https://www.mayoclinic.org/diseases-con ... c-20350860
Anyhow, if kids undergo treatment beginning at a few months of age until about 5 they end up almost completely fine. Your foot is a little shorter and wider than normal, but everything is basically fine. The braces looks something like these. It is just an adjustable bar that you can make wider over time and a set of shoes that clips onto the bar.
The two main problems with this is that 1) children require many many sets of these braces as the grow from a few months until 5 years old. This has been a real boon for the few companies that make these braces because they need to be replaced over and over. While most children in the US are covered by their insurance or Medicaid children in developing countries can not afford these at all. We would collect used ones and take them to these countries to help out where we could.
I got as far as drafting up a bar and footplate to hold the shoes but no further.
If anyone is interested and thinks this is actually feasible maybe we can get together and donate a few hours here and there until we get this done. I could try and get people to donate money on one of those fundraising sites to see if we can print out prototypes to make sure the shoes scale properly from kids a few months old to about 5 years old. Once we have the final design we can just publish it for free and also provide directions on what materials would be most appropriate. The upper part of the shoe would need to be somewhat soft and flexible.
I know a group of people did this a while back for a 3D printed hand/arm prostheses with great success. I believe they even had a network of volunteers who would use their printer to print the prosthesis out for kids in need.
Anyhow, It will be a lot of work but I thought I would just throw it out there and see if anyone wants to try and make a small dent in the world's problems.