The nut slots *should* be just the width of the string, half the depth of
the string, and round at the bottom.
If they "pinch" at the fretboard side that prob means the other end is too
wide and the string will buzz... And there's more likelyhood of string
breaks.

If you put the string in the slot and move it from side to side then the
other end shouldn't move. If your bass string slots are too wide then I
think that thicker strings have been used at some time.

In my original message I said I wanted to print a "grid".. But this was
probably a bit misleading. What I'm doing is colour filling columns for 10
rows and then setting column widths and printing.