The utilization of recycled plastic waste as a new raw material for 3D printer filament is one of the strategic approaches to support recycling efforts and reduce plastic waste pollution. This research aims to design and develop a filament extruder device based on the ESP32 microcontroller, which is used to convert plastic water gallon waste made of Polyethylene Terephthalate (PET) into filament suitable for use as 3D printer material. The system design involves several processes, including cutting plastic from gallon containers into strips, melting the material, extrusion, and filament pulling. In addition, data acquisition is carried out through a local host web interface to monitor and control parameters during the extrusion process, such as the heating system and the drive mechanism using a NEMA 23 stepper motor. The measurements and analyses performed in this study include evaluating the consistency of the plastic strip width after cutting, the dimensional consistency of the resulting recycled 3D printer filament, and analyzing the stability of the heating system by assessing the influence of the beta constant (β) on the thermistor and the PID control applied to the heater. This research is expected to contribute to the development of plastic waste conversion technology into value-added products, particularly in the form of recycled 3D printer filament derived from used plastic gallons.