Battery Lark
Making lithium ion packs is really a weird craft. The power output of the things is so intimidatingly high that even a brief short can make things glow a bit, and you get that weird air ionizing smell. It seems like it would be easy to avoid shorts, but minor ones seem to want to happen from time to time. Fortunately it's not dangerous to get a brief spark, but it's definitely a scare when something goes crackle-pop. It is pretty neat to be able to assemble something with that much power and capability, though.