Are you a startup, and are you developing a new hardware (physical) product?
Are you planning to raise money to finance your project?
The typical investor becomes more interested as you complete milestones that prove your project is less risky and is getting closer to the desired result – a profitable company that has real customers and some unique intellectual property.
The milestones that make sense may vary from project to project, but investors consider them as fairly consistent. This is generally applicable for projects that represent between 100,000 and 1.5 million USD.