This is a facility to keep a metallic ruler vertically standing, to measure-align vertically without the need to keep the ruler by hand. Two M8 screws are used in V2, to avoid problems with small cross section plastic screws. Use of some silicon grease on the screws prior their first use is recommended.
The M8x16 part is based on the design by Devious (Metric bolts and nuts fit steel Metric bolts and nuts (V2) by Devious | Download free STL model | Printables.com), but modified for shorter screw length.
I'm including also the freeCAD file for everyone to adapt accordingly. My ruler has a cross section of 26.30x0.90 mmxmm.
Prusament PETG was used successfully.
The author marked this model as their own original creation.