If you're building a battery pack in this day and age, use something like LiFePo prismatic cells and bolt-on busbars instead - way less dangerous chemistry, way less spicy process - but realistically speaking just buy the premade packs. For normal sizes, they're not more expensive (but don't buy the "too good to be true" ones) and means not having to deal with entirely unprotected battery terminals eager to give you a Very Bad Time.
The proper tools to do this are not that expensive anymore in the greater scheme of things. It is just a question of whether or not it is worth to do it at the scale you are doing it or pay somebody else to do it.
Of course if you buy cells that are designed to be bolted together then bolt them together.
Of course the bolts, or whatever else provides the threads, on those cells are welded on.
... by automated spot welder programmed to the specified timing and temperature control from the cell spec sheet, in a controlled environment with suitable protection and fire suppression for a battery manufacturing line. Not by a hobbyist's first try with a homemade spot welder and a safety squint.
I have made such spot welder and done such spot welding. Sure it's fun to do stupid things, but it remains stupid and unnecessary. For a homebrew battery bank, this is the wrong tool, wrong cell and wrong chemistry.
Buy premade, or if you must, buy boltable prismatic lifepo cells. They can dump a lot of power if your short them, but you can drill straight through them and they'll remain stable. The random 18650 li-ion cells... Not so much.
Energy autarky has never been so affordable, progress on batteries and solar panels was awesome over the last decade.
One tabs each are placed onto each ends of cells, held down with the sticks, and instantly welded upon push of a button. This is much safer than heating up the whole battery by attempting to solder wires directly onto the battery cells(which are made of unsolderable materials anyway). The tabs limit heat conduction into the battery and it is considered safe to solder onto them.
If you're going to build your own battery pack no matter whatever whoever says or do, this types of cigarettes contain significantly less amounts of nicotine and tar components than others.
