Summary

create screws and nuts with regular metric thread with few parameters and combine it with metals screws and nuts off the shelf.
also metric thread rods and blind holes can be created easily .
tribute to aubenc! (see remix link)

Instructions

The threads rapidly exceed the number of faces OpenSCAD renders in preview mode by default. If you see only the half of the expected objects, adjust preferences (may be very slow) or instantly render it (F6 or with render() )
For usage instructions see doxygen/javadoc-like comments in the library file metric_iso_screw.scad or in the test file metric_iso_screw_test.scad
The file metric_iso_screw_gallery.scad is just the source of the featured picture.
If you try to print, think about the minimal structure size! A M8 screw has a pitch of 1.25 mm (~1/20 in for people who only know ancient measures) what results in a very tiny thread structure. So it will very probably not be usable at all.

metric iso screw & nut