Thats just it. He's having trouble getting lots of small donations. Maybe he could get fewer large donations.
So what money is he using now to pay his directors, build his prototypes, and advertise his t-shirts? I don't think stock plays well either. Your stock can still be worthless at the end of the day.
To address your house example, yes, there would need to be a point of no return in the near future. So he wants to ramp up in Q3-2015. Worker hires need to happen Q2-2015. I would say we need to have the $200 mil raised by then end of Q1-2015. So come 1 April (ha!), we hand over the check or refunds all around.
And donation is the wrong word... pledge maybe?