Damn. I need to go home and think about my life.

Not the spacing, but it affects the width of the lines.

Exactly - my “pen” is a stainless steel nail in a 3d printed housing.

I make the print by anodizing - I have a pen plotter I converted for this and I use the cathode as my ‘pen’ to print the image.

Thank you!

Very similar! Both colors are formed by oxide layers on the surface, I think with stainless steel it’s a mixture of iron and chrome oxides. In the case of titanium there is only one oxide, TiO2, which is transparent crystal (in thin forms). The TiO2 layer is thin, on the order of hundreds of nanometers so the colors you see are a result of light waves constructively and destructively interacting with the transparent layer of TiO2 on the surface of the titanium sheet.

Flawless logic, fantastic post