First, here is how the embellishments look on the page: (with some metal behind the book)
And here is the process: metal duct tape (found at hardware and auto stores) covering a sheet of craft foam (for this I used a teal color as it matches the colors on the page), and then doodled with Sharpie extra fine permanent markers. I find that I am having to go over the doodles again to make the marks really black. The foam really holds the "engraving" of the line. You don't get it from these photos, but I painted a layer of pale green nail polish (wasn't my color) over the top. It looks wonderful with the other greens on the page.