Having fun with analog electronics. Turns out it’s much more fun (and challenging) to eschew microcontrollers. Lots of things can be done with op-amps, comparators, 555 timers and some of the intermediate-complex stuff can be done using CMOS4000 series digital ICs. All of this is dirt cheap! Even those 4000 series ICs cost a third of the cheapest 8-bit AVR micros.