Extrusion.
Extrusion is a manufacturing process used to make
pipes, hoses, drinking straws, curtain tracks, rods,
and fibre.
The granules melt into a liquid which is forced through
a die, forming a long 'tube like' shape. The shape of the
die determines the shape of the tube. The extrusion is
then cooled and forms a solid shape.
The tube may be printed upon, and cut at equal
intervals. The pieces may be rolled for storage
or packed together.
Shapes that can result from extrusion include
T-sections, U-sections, square sections, I-sections,
L-sections and circular sections.