It was made to be robust, but it still had to be born in the eutactic 
womb, a solid diamond vacuum chamber housing a start matter compiler. The 
diamond was doped with something that let only red light pass through; standard 
engineering practice eschewed any molecular bonds that were tenuous enough to 
be broken by those lazy red photons, underachievers of the visible spectrum. 
Thus the growth of your prototype was visible through the window—a good 
last-ditch safety measure. If your code was buggy and your project grew too 
large, threatening to shatter the walls of the chamber, you could always shut 
it down
via the ludicrously low-tech expedient of shutting off the Feed line.