In my last full time employment I found myself in a nondescript cube counting down the hours to lunch and then till quitting time. There were four hours till lunch, a one hour break and the another four hours till the end of the day. It varied very little from that. There were conference calls to take up some of the time, but I realized I was just counting down four hours and repeating it after lunch. So I devised an animated hour glass. The display is an 8x8 LED matrix representing sand dripping through an hour glass. It takes 4 hours. Then the whole display rotates 180 degrees in a one hour period, after which the animated sand displays again for 4 hours. The Arduino does the counting, displaying and servo control. During development I added a "demo" switch to show the display and servo operation in a shorter time span.
Once the code was worked out with a friend's help, it was wired up on a breakout board.The prototype uses an Arduino Uno; An Adafruit LED matrix and backpack. This way you can use I2C for driving the display with 4 pins; A servo from Parallax as I needed one that could rotate 180 degrees. I tried a simple RC servo, but it did not rotate 180 degrees only 90. To use "Demo" mode, hold down the pushbutton while applying power or pressing the reset on the Arduino board. The Matrix will scroll "DEMO MODE"
Step 1: Obtain parts
1 x Ardunio Uno
1 x Parallax Servo ( 180 degree rotation)
1 x Adafruit 8x8 LED Matrix with I2C
1 x Momentary pushbutton
The Arduino IDE for loading the software.
Adafruit provides a comprehensive library for handling the LED matrix.
Hour Glass sketch.
For a finished hour glass you could burn an Arduino with the boot code and program code and save money on using a whole Arduino Uno. You will also need a box to hold the components while allowing the servo to rotate the LED Matrix. Make sure the wires are flexible enough to allow the servo to rotate without snags or too much wire tension. You will have to consider batteries or a wall wart supply for power.