The soldering gun is useful when soldered joints must be made intermittently.
This is needed for making soldered capillary joints.
You will also need flux for making soldered joints.
A degree of skill is needed to rapidly make large numbers of reliable soldered joints.
They are constructed without soldered joints, rivets or screws.
I opened them up, and saw they'd used inferior components and the soldered joints were bad.
The solderability of a substrate is a measure of the ease with which a soldered joint can be made to that material.
In general a good looking soldered joint is a good joint.
It has to "remember" the different types of components, their positions and also to check the quality of the soldered joints.
Look carefully for soldered joints, often well-disguised by the experts of the time.