Wire a compact OV7670 camera to Arduino to capture images and stream them serially to a computer, with a technical note on operating voltage.
Build a robot that automatically follows a drawn line using two IR reflectance sensors and an L298N motor driver module.
Wire a simple mechanical tilt sensor that acts as an on/off switch when an object's orientation changes, with no calibration needed.
Turn an MPU-6050 module into a digital protractor that shows the angle both digitally and mechanically via a servo motor and pointer.