Is purchasing a product idea and manufacturing it for personal use at a lower price, knowing its original cost, considered theft or an infringement on the product's rights?

Inventions and innovations are intellectual rights owned by their creators, and it is not permissible to infringe upon them. However, benefiting from a product idea without exact imitation is not considered an infringement on the product owner's right. Shaimaa Al-Nadi, in her thesis "Patent in Islamic Jurisprudence," mentioned several forms of imitating an invention, clarifying that the fourth form, which is benefiting from the working method of an invention without adhering to the original inventor's steps, is not considered an infringement on the inventor's right.