So I was so excited to have all the programming working exactly how I liked, including a sound effect to play when the weapon is fired. I got all the materials together and started soldering - and fried my circuit board. Sigh.
I'm going to give it another go before begging for a friend to do the soldering for me. I'm really hoping to get the hang of it so I can work on other projects. But it was a big set back.
My plan now is to get the battery pack soldered on first, make sure the thing still works, then add pieces in smaller groups and check at each stage that everything still turns on and works. Not sure the best way to go about that as things will need to be all grounded together, though I suppose I can ground things in groups. The Pi Pico has several ground pins.