Inspired by a Sunday fun rolling dice, one afternoon I ventured to build my own dice on a protoboard.
The heart is an ATtiny45 (but you could even use 25, as the firmware is less than 1k). I didn’t want to disable the reset on the attiny, so that left 4 IC pins for LEDs and one for the button. Since we need to control 7 LEDs, one can either multiplex, or just wire the opposite LEDs to the same pin. As the second is simpler and sufficient for a dice, I opted for that solution. I used a slightly modified firmware from the above website. One cool thing about it is the automatic sleep mode, which saves power.
The wiring is not nice, as some wires cross - but it wouldn’t take much effort to straighten it out and avoid crossings. Next time ;)