This calculation is incorrect. When we had 100 donors each donating 500EUR then we had 50k obviously, but we need to ship 100 devices for that money plus 100*difference-to-sales-price. So zero "excess money" available anywhere in all this. This calculation holds no info at all. we need to build - at least - 200 devices to make fab operate in (semi) economic range. It would differ if we had a donated value of >700EUR per donor, then we actually could talk about "excess money". /j