Last weekend's small DIY project
I really enjoyed this. I know it does not look like much, but I am very happy about this little project: I finally learned how to solder properly and lead-free, and I now understand AVR microcontrollers architecture and specifics. What’s left is to finish power optimization and start periodically add different sequences for LEDs and different reactions to button clicks. And I also learned about powering small devices and about Joule Thief / step-up regulators, induction, surface-mount and PCB design/ordering (however, these are not used in this project)...