The vast majority of FDM (fused deposition modeling) 3D printers primarily consume ABS or PLA filament. ABS, a petroleum based thermoplastic, is a little tougher and bit more flexible than PLA, but also a little more finicky to print with. ABS generally requires a heated bed to reduce warpage, and also emits a potentially troublesome scent as it is extruded. PLA on the other hand, or poly lactic acid, is derived from starchy sources - most often sugarcane or corn starch and has a far more palatable (some note a breakfast waffle-like) scent when extruded.
The marketing writes itself. PLA is a natural, bio based alternative to petroleum laden ABS! Sounds (and smells) like you could eat it! I'm a hands on guy so I tried a nib, tastes like plastic. The baked out, boiled down, unsweetened truth is that it is indeed, plastic. Marketeers love to tout the biodegradability of the material, and its true, that at some point it will biodegrade. The reality however, is that this process will take several hundred years in a typical landfill. To biodegrade, PLA requires a laundry list of conditions to effectively break down. Specifically - oxygen, a temperature of 140+ degrees, and a 2/3 cocktail of organic substrate. Collectively, these are absent in any scenario outside of industrial composting facilities. This means that PLA plastic will sit in that landfill right alongside ABS and other plastics for a very long time.
When considering the environmental friendliness of a particular product, it is essential to consider the amount of energy used to create that product. For all plastics, the energy required is particularly significant. This dictates that the ultimate waste of that energy is to literally discard it. For this reason, keeping the material in its intended physical form is far more responsible.
What do we propose? Print responsibly and recycle accordingly. The Filabot, for lack of a better engineered example, is capable of turning your old PLA prints into fresh filament again so you can indefinitely extend the practical life of the material. Plastic, once it has been industrially produced, is categorically best staying plastic. Giving this plastic renewed purpose is the key, and is ultimately a far more productive future than an impractically slow death in the ground.