PLA

PLA is eco-friendly plastic. It is produced from plant-based components and is biodegradable.

This plastic has traditionally become the easiest type to print - it is known for good adhesion to print bed and between print layers. It also can work without a heated bed and open printer frames.

It is sometimes considered not solid enough for mechanical appliances, but this is not really true - modern PLA filament has proven itself to work for years without any visible change in structure and color.
Of course, it won't last that long if it will be hardly used when exposed to higher temperatures (like +50 C and more) with an intensive UV environment - but this should be challenging for almost any material.