I think he was telling Edible in particular not to solder them. All my packs are self assembled, the cells have metal tabs which you solder to. You have to be very careful as they are fragile as anything, the tabs don't take much abuse before breaking off and too much heat will break the seal, potentially resulting in a fire.

Out of 20 odd packs only half were preassembled and they were later partially stripped to allow cell balancing.

It can't be stated enough however that unless you are fully confident about what you are doing you should buy pre assembled packs only.

--
Dave