Plastic built by food poisoning (sort of)
Apparently bacteria can be engineered to produce thermoplastics. This is not a fact I knew and is casually mentioned on the website of the BiOrigami team of undergraduates from Standford and Brown universities who are developing a method of producing plastic and then causing it to fold into useful objects based on E.coli bacteria. This is rather different to injection moulding or extruding an object!
The motivation behind the project is to allow tools to be produced in space by astronauts, for example, on flights to Mars, to help reduce the weight of equipment taken.
Website link: BiOrigami Stanford-Brown