Papermakering

[…] said drainage means and forming fabric being inclined with respect to said papermakering felt; a head box positioned at the beginning of the forming fabric for placing stock thereon; […]

A non-limiting example could have a sheath comprised from any fiber forming thermoplastic suitable for use under papermakering dryer conditions (hydrolysis stabilized PET), and a core comprised from a fiber forming thermoplastic (PET) Which has been modified to include 40 volume percent or more of gaseous bubbles.