a frappuccino fresh from the phone

Along these lines, wouldn't it be interesting if we had a technology that would be our perfect biological complement, that would nourish itself with our waste products, and produce waste that we could use as food? Think of a robot that would eat our fecals, drink our urine, and in turn produce, say, vanilla pudding with chocolate sprinkles, while being perfectly happy about all that. I think something like this might be possible, and that there is no inherently decreased evolutionary quality to things we consider to be waste products. Only from our own biological frame of reference this is so, but if we can create other forms of life than merely carbon-based ones, I think we could surely have a biological complement.