Found some printable M8 screws on Thingiverse (https://www.thingiverse.com/thing:4805480), which made me wonder if I can get M4 screws, just by resizing them factor 0.5.
The ISO metric bolt has its diameter as the numeral part of the name.
So M8 has a diameter of 8mm compared to that of the M4 bolt. So far scaling would make sense.
However, the pitch of them is not proportional and would be wrong if you scale them.
her is a figure from Wikipedia. Wiki