I'm wondering if it's possible to make LEDs, displays and semiconductors using a big ion deposition machine. The machine would be like a very slow and doubtless huge 'replicator' that can manufacture a wide variety of things by spray-painting atoms onto a substrate. Ideally the device would also dissociate and purify the silicon, metals and other substances as they are used, like a mass spectrometer; it would not have to be frequently dismantled for cleaning or maintenance (unlike a mass spectrometer); and it would not contain anything extraordinarily rare or costly. If anyone takes an interest, how big would such a machine have to be for a yield of, say, a gram of product per day? What would the basic design look like? Right... I'll get it started myself by calculating the obvious. Lets assume that what we're making is mostly silicon. One gram of Si is 2.7 x10^22 atoms. That's 4.4kC (4400 'coulombs') of Si per day (assuming the atom stream is of silicon atoms with one extra or one missing electron); which comes to just 50mA. That's a lot for an ion gun. It's a lot even for 100 ion guns. Using many guns in parallel confuses things a bit. Maybe one biggun? My purpose is to make electronics and reagents without pollution or mining.