I just printed another version of a Z-stop adjuster. It uses M3 screws and an oversized knob with 20 dents so that each dent changes the z-limit by 0.025mm, a full turn is 0.5mm. Maybe an overkill, but it printed, unattended, in 5' at 150mm/s.
I think red does not go well with the Hadron colors.