Molding corrugated pipe - GIF

Molding corrugated pipe.

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Previously:

Corrugated mesh roller - GIF
Corrugated metal roof making tool for modeling - GIF
Corrugated pipe extruder - GIF
Corrugated plastic cutter - video
Corrugated roofing shear - GIF
Making a corrugated elbow - GIF

They don't show us the part where they drill out the center.

Why is that pipe orange rather than black? Is it for a different sort of fluid?