Marking Gauge

This gauge fits on the classic metal ruler (profile of 13x0.5 mm). It fits snuggly while it can be adjusted with reasonable force.

I use a nice brasse M3 hex spacer and a M3 nut. 

No rounding or chamfering has been applied to the model to get the most accurate geometry.
PLA prints fine. Maybe PETG would be the better choice for woodworking.

Update 20230120:
Made some minor adjustments to the tolerance settings and overall dimensions (v11).
Added a little knob to replicate a finger screw, needs a M3 heat set insert.