Heat crawling up the hot end like this is known as heat creep and there are a variety ... heat-break and a fan can do the job for common 3D printing tasks, there can be problems.

A NIMS research team fabricated heat-resistant steel test specimens using laser powder bed fusion (LPBF)—a form of metal 3D printing—and subjected them to creep testing for up to 10,000 hours.

The basic process is simple: tightly wind some 3D printer filament around a steel rod, secure it and wrap it in kapton tape, then heat it up. After cooling, one is left with a reasonably ...