Between the socket and the arm is the flexible union, we have made it a flexible ninjaflex filament. This part is very important since it ensures the fit between the arm and the socket.
In order to make the model we had to make several tests, the flexible union must have the measurements of the stump for the precise adjustment but achieving this can be a real headache if we do not use the right tools.
At first we tried with eye and tape measure what did not give us good results (obviously), As seen in the images, sometimes the union was very small and sometimes very large.
There are 3d scanners, but at that time we had no possibility of obtaining any, which made us try with 3d photogrammetry, It was a new method for us but we tried it with some dedicated programs for that purpose.
At the end we choosed by Autodesk Recap, although in its free version every time we want to generate a model we must wait in line until there is space on the server, in our case it was something like 24 hours.
The images that we created to generate the 3D model were something like this:
And the result was something like that:
After the model was imported to fusion 360, with this it was possible to generate the model of the union with greater precision