There are a few options you could consider if you want to build a prototype for a highly capital-intensive project but don't have any money:
Look for grants or funding: There may be grants or funding opportunities available for your specific industry or project. Do some research to see if you might be eligible for any of these.
Crowdfunding: Consider using a crowdfunding platform to raise money for your prototype. With crowdfunding, you can pitch your idea to a large group of people and ask for their support in exchange for rewards or equity in your project.
Partnerships and sponsorships: You may be able to find a company or organization that is willing to sponsor or partner with you on your prototype project. This could involve providing funding, resources, or expertise in exchange for some form of benefit (such as a percentage of profits or recognition in marketing materials).
Bootstrapping: If you don't have any outside funding sources, you may need to find ways to build your prototype on a shoestring budget. This might involve doing as much of the work as possible yourself, using low-cost or free resources and materials, and finding creative solutions to stretch your budget as far as possible.
Keep in mind that building a prototype can be a complex and time-consuming process, so it's important to carefully consider your options and choose the approach that makes the most sense for your specific situation.