This is a ruler model that was modified to make it a flush-end ruler - the measurement starts right at the edge of the ruler rather than there being a gap from the edge to the first measurement line.

I recommend using a lighter color for the body of the ruler itself and then filling in the numbers with a darker color. I went with gray for the ruler and black for the numbers and lines.

Any filament will do. I recommend using a smaller layer height due to the details. I used 0.16mm. This will increase the print time significantly but you'll find that it is worth it.

My printed example is not a reflection of the quality of the model. I realized at the last second I only had so much gray so I had to reduce the amount needed. Your's will be much nicer!