This paper describes the development of a low-cost home-made microcontroller based temperature control system. The system has been developed to support the practical sessions in undergraduate teaching of the automatic control theory course at the Near East University. The thermal plant was made from a plastic box consisting of a low-voltage heater and a semiconductor temperature sensor. The temperature inside the box was controlled using a microcontroller development kit employing a PIC18F4520 microcontroller, and providing a PWM (Pulse-Width-Modulator) output for the heater. Various digital controller algorithms and PID tuning methods can be programmed and tested using the kit. The developed kit enables students to control a laboratory scale thermal plant by learning to program the microcontroller in C. In addition, students can learn the principles and application of the important relay-based PID auto-tuning algorithm to control the plant.