My most "serious" DIY project: build a infrared thermometer by MDF 3mm case, cut by laser. Electronics component from Arduino, OLED screen, and infrared thermometer sensor GY-906. It looks perfect, right :) ? :
DIY Temperature Thermal Gun | MLX90614 Contactless Infrared Temperature Sensor with Arduino - YouTube
Arduino Project: IR thermometer using the MLX90614 IR temperature sensor from icstation.com - YouTube
Sensors | Free Full-Text | Design and Development of a Low Cost, Non-Contact Infrared Thermometer with Range Compensation
An open-source non-contact thermometer using low-cost electronic components - ScienceDirect