Would fit in anticounterfeiting laws so, probably illegal, specially if the pieces aren't clearly marked as different from the original brand, and much more specially if they are designed for replacing the originals in public health purposes.
Counterfeiting in clothes is one thing, counterfeiting in hospital matherial, when even perfect products can be accidentally contaminated with biological matherial and create lots of problems (or even kill people)... Well, this plays in a very different league.
And cloning devices of course opens the door for other companies to crush the original maker flooding the market with cheaper products exactly when the maker rely on benefits to recover their money (after mass producing products). I assume [1] that there are laws also against this.
[1] I'm not a lawyer and could be wrong. Your mileage may vary.