Crowdfunding is the best way to both get cash and to show traction. That is a bit of a hit or miss scenario, though, and compared to the early days of Kickstarter, the chance to be successful has dropped because the number of tricksters on there and the media fatigue to report on those stories. Still, it is an option.

Investors familiar with hardware will know that traction isn’t a good metric. Unfortunately, since software has become the dominant model for your average startup investor, there are fewer suitable investors. Try to look for VC firms or angel investors with a stated interest in hardware or electronics.

I don’t know where you are based, but another model I’ve seen used in East Asia is to do a deal with the contract manufacturer. They are often huge with capital reserves, and they may effectively act as an investor by allowing deferred payments given some equity. These deals require some good “schmoozing” with Asian factory bosses, but they have happened.

Maybe there are other types of partnerships to exploit specific to your product type or academic connection or geography. Government grants, partnerships with bigger hardware companies etc etc....

It isn’t easy, but there are paths to get it to work. Good luck.