PCB Etching with 3D Printer Agitatior

I made Tech2C's Pen holder https://www.thingiverse.com/thing:2459624
I used it on my Milling machine to apply sharpie ink as an etch resist.

Here is a video https://youtu.be/vKqAf8pkKJ0

Then I used my 3D printer to heat and agitate the Ferric Chloride solution with the pcb in it.

GCODE
g1 y0 f4000
g1 y50
g1 y0 f200
g1 y50
make many copies of this. Takes about 15 seconds to execute.

You can see the sample pcb traces that I produced using this technique. I would increase