A sturdy and filament-saving wrench holder for these [metric] sizes: 5.5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22

It's not just a simple holder - it's designed to carry the wrenches. Accordingly, the wrenches also stay in place when carried upside down.

Six screws in M4 (and an M4 thread cutter) are needed. The length of the screws is not that important....between 10 and 20mm.

The sizes can be customized in the scad-file.

UPDATE 18.01.2020: added a version with angled openings.