Wanted to make an arm that could be used my most people and grow with them to some degree. If printed with PLA plastic you will be able to heat it up with boiling water and adapt it to make the individual. Also the arm can be sized with the recipient on the same day by using a PVC pipe. Just cut the pipe to match the length you need then use Hot water to mold the plastic and you're all set. Not to mention it would be able to grow a bit with the user by resizing with hot water or lengthening the pipe. https://www.youtube.com/watch?v=HJxMAjIxFr4 https://www.youtube.com/watch?v=-4DGeAK3EFI