I think capacitors with a blocking diode would be the right call..
That calculation clears up so much. Really great explanation, thank you!
It seems a diode is needed either way.
The power supply runs both the Arduino the blaster itself, which means the two motors it uses. One motor spins the barrel (purely as an optical effect), and other one actually shoot out the darts.
for a hobby level project maybe simply going 10x for a few pennies more would be a good idea
Glad to hear that (other than cost) there is no problem with using a way too big capacitor. That also simplifies building up a stock