Center Scribe Measuring Tool

I made a block to be able to move the ruler by a thumb screw instead of 4 Flathead screws.

I bought the tool from Amazon
https://www.amazon.com/gp/product/B07RKJSZ6C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You need 4x M5x0.8 screws and 1x M8x1.25 Thumb screw.
I will make a protection tip for the thumb screw later, but for now, putting a tape will be enough to avoid scratching the ruler.

** Update on May 12th
I made the tip.
I used a thumb screw I had and made a hole and glued the tip.

If you don't mind to buy some hardware.

https://www.mcmaster.com/93285A136

You can print or buy a thumb knob for the set screw.
https://www.mcmaster.com/thumb-knobs/system-of-measurement~metric/thread-size~m8/mount-type~threaded-hole/