For the second fabrication approach, I created my own .svg file to import into Otherplan and mill. I started with icon vectors I have and adjusted them according to (what I thought were) the router's requirements. I varied the stroke widths and object joins to test different effects but the one thing I forgot to vary — file numbers themselves— turned out to be the most important.
The first attempt at cutting got the circles and the whale's eye and mouth, and some of the darker crystal overlaps but the rest was ignored. In order to salvage them, I think I would have had to load two files, as in the chocolate mold tutorial but the easiest thing to do was invert the engraving cuts in Otherplan. This resulted in mostly-cut talismen, and I love them both.
But, for my final project, I will be making a mold similar to the one linked and for that, I will be using two files!