If I make a prototype of my invention after having filed the application for patent but without having it granted yet, are there some risks? Could others gain advantages by seeing what it looks like?

After having deposited the patent application, and even before it gets granted, the patent holder is protected from the legal point of view to all effects. It is true that the application remains secret for a minimal period of 90 days and maximum of 18 months, but this does not mean that the requestor has not been given a definite date from which his rights would be recognized. The realization of a prototype, therefore, is quite possible and will not cause any damage at all. The fact that the object of the invention gets made and maybe even displayed, prevents others to patent the same thing overseas, thing which in theory is possible until the patent is kept secret but becomes not feasible once the invention has been in any way made public. From this point of view the making of a prototype is not advantageous for the competitors, even if they get to know how the object is made. On the other hand, the patent gets indeed deposited to avoid any plagiarism of the products; therefore it would be absurd to wait for the granting of the patent. The only thing to ascertain is the date of “publication”, chosen at the time of presenting the patent application, as this is important because it marks the moment from which action for damages can be taken against counterfeiter. Even if it was kept secret, however, the patent holder can still stop the plagiarism by giving a notification of the text of the patent to the person or company who is copying it.