Does building a guitar involve any soldering?

Depends on the guitar. Acoustic, no. Electric, yes.

If the guitar has a pickup of any kind, then they would likely have to solder at least the pickup wires to the circuits attached to the pickup selector (if it had more than one as in a Gibson SG or Fender Stratocaster) and the and the volume and tone pots.

The helping hands tool would not be strictly necessary unless the character were a klutz like me – I need all the help I can get with fiddly work.

I imagine the helping hands device is great for making fly fishing lures. Which is a very artsy-craftsy hobby.

I’ve got one of those. I do use it for soldering, but it’s a handy thing to have for gluing small parts, too.

When I use it for soldering, it’s usually to solder wires together, or to solder a wire to the end of a device lead or other small part. For example, an LED that I would detach from the circuit board to use as a pilot light or indicator. I’ve never worked on a guitar, but if I did, I don’‘t expect I would need it. As long as one of the things you’re soldering together is anchored or heavy enough not to move around when you touch the iron to it, you generally don’t need the clips.

You could use it for painting tiny details on just about anything. The clips could be good for keeping the item stable as you worked on it, or for working on something so small that your fingers could obscure or smear the work.