Solar thermal applications vary widely across many different fields. This research aims to introduce the concept of using solar thermal energy in a new application for recycling waste plastic for use in 3D printing. In some countries or regions, waste plastic is not collected for recycling and thrown into landfills. This leads to serious local and global environmental pollution. In additive manufacturing, plastic is one of the main materials used to build 3D models. In this work we suggest a novel way to produce extruded filament for 3D printing from waste plastic using solar energy. The concept relies on using a Scheffler fixed focus solar collector to heat the barrel of a filament extruder rather than using electrical heaters. The barrel of the filament extruder is heated by a receiver in the focal point of the solar collector. The molten plastic is then extruded through a nozzle to produce filament. This concept of using solar power for extruding 3D printing filament is an environmentally friendly way to turn waste plastic into useful 3D printing material especially in areas where recycling of plastics does not exist and electrical power is limited.