Holes for the seam - 1mm with a step of 5mm (in some areas of the rounding, the step floats from 4.85 to 5.1 mm, so I hit everything with a single punch).
Assembly of FEV V4.5 S+ tank from ULTON components
Probably the fact that when inserting the droppers I didn’t wet them and the O-rings on the droppers were cut off a little played a role, maybe I didn’t put enough cotton wool or it was the droppers themselves, but with the FEV V4.5 S+ from YFTK I had overflows.