Here are the files for my version of a battery cell spot welding jig. It can also be used when soldering cells. It's intended to be adaptable so can slide between points to support combinations from 2x1 up to the maximum of 10x4 cells.
For 10x4 (40 cells) you need to print two of each part type so 2x long & 2x short.
For a maximum up to 4x4 (16 cells) you need 4x short parts.
For 10x10 (100 cells) you need to print 4x long parts.
4x M6 butterfly nuts
4x M6 25mm rods
4x M6 washers.
I first drilled & tapped M6 threads into the holes in the parts before using some superglue on the threaded rods to lock the rods in place.
I printed this in PETG with four walls top & bottom for some strength along with a 15% infill. This will also print fine in PLA.