Build a countdown timer with hours, minutes, and seconds set via a keypad and shown on an LCD, with an audible alert when time runs out.
Wire a KY-040 rotary encoder to precisely determine rotation direction and step count, showing the value on an LCD.
Build a simple calculator with a 4x4 keypad and an LCD screen that performs addition, subtraction, multiplication, and division.
Build a standalone digital LCD voltmeter that measures voltages up to about 55V using a simple voltage divider.