Actually, it is usually OK to use other peoples ideas, even if you do profit from them. Sorry, but just because someone has a specific design, does not make it their right to exclude others from it. Unless it is unique enough and valuable enough to have had a patent applied for and granted. And even then, a great many patents are would not hold up if challenged. Patent examiners do a pretty crude job. It is left up to patent lawyers to sort things out.
This is also why we have the patent system. Disclosing your invention allows others to modify it, to improve it, and to further technology. In exchange you are allowed to profit from it for a specified period of time. The whole idea is to share inventions to further mankind. It is NOT to protect your technology. Companies, particularly drug companies, will NOT patent processes for making valuable drugs because to do so would require them to disclose it. However, they may obtain the composition of matter patent for a new compound.
What would the world be like if no one made cars but one person, or wheels, or pants, etc. Your selection would be crappy and the products poor.
Even if a misguided manufacturer gets upset by someone using a similar design to theirs, truth is, in the long run it will benefit everyone as the competing design will have improvements, that he can then also copy into his product. It is a constant, iterative process to improve technology. To avoid it, is to stagnate.