I'm not a fan of getting up in the dark, so I created an arduino-based system that would turn a light on slowly in the morning to simulate a sunrise.
I wrote the code to run the alarm and provide a convenient user interface. I designed, produced and assembled a circuit board, and with the help of a friend with CAD experience, designed a housing that I 3D-printed. The resulting product has served faithfully at my bedside for years.
This has been an on-and-off project of mine since 2014 (depending on how you count--those were some very early prototypes), and has resulted in a lot of learning opportunities.