Nylon
Very strong, nylon can be machined and will take a fine thread. It is also slippery and can be used to make washers, spacers and bushes.
Nylon was originally developed as a textile but is available in many forms with vastly different properties. Engineering nylon grades are easy to machine with good resistance to biological attack. Unfortunately nylons can absorb moisture from the atmosphere and can degrade in strong sunlight (they are unstable in ultraviolet light) unless a stabilising chemical is added at the initial manufacture of the plastic. Nylons are easy to mould. Nylons also have a natural 'oily' surface that can act as a natural lubricant. Nylons are used for everything from clothes through to gears and bearings.