What is harder than pushing a rope? Try pushing a ribbon! This pushing needs to happen between the extruder drive assembly and the heated portion of the hot end.

How can we make the ribbon less flexible? My solution is to crease it into an L or U -shaped cross section. Using an angled-surface drive pulley and an inverse angled bearing surface, this should happen quite nicely.

This will push a temporarily stiffened ribbon into the hot end assembly where it will be heated and deposited.