For precise woodworking projects I use steel rulers to measure and mark: a small stopblock is a nice addition to transfer repeat dimensions.
I like the Rumold steel rulers,  they come in various lengths: Art. 323713 - 300mm / Art. 323715 450mm / Art. 323716 - 600 mm / Art. 323719 - 1000 mm. 
But the block should fit any any steel ruler with the same dimensions. 
If your ruler is not there, let me know and I'll try to add a new size.

Update 30-11-'24

I added a few model files for different size rulers (width x thickness):
25x1mm
26x1mm
30x1mm
35x1.2mm

Printing:

Printed in ASA with nozzle 0.6 and layer height 0.2mm, 2 perimeters, infill 20%.
Added some support for the hole only.
See picture for print orientation.

Hardware: 

A steel ruler with the listed dimensions.
One brass heat insert M4, 4mm thickness, 6mm diameter.
One M4x8 hex screw, or cut a longer screw to length. 

Assembly:

Clean up the block, so the ruler slides nicely in the slot. 
Press in the brass heat insert.
Make sure the end of the screw doesn't have sharp edges which could damage the side of the ruler. 
Glue the little grip cap to the head of screw.

Bart