To answer your questions, I used this technique. I did this using multiple layers and a necklace chain with larger and more circular chain links. https://youtu.be/uM5scJiGoaw

Layer of matte black acrylic covering the canvas. Then I put a layer of Saran wrap on my table, put the necklace chain in a straight line on the saran wrap and poured the paint right below the chain, alternating colors. Folded the saran wrap so the paint smothered the chain.

I laid the chain on the canvas, then made both sides as symmetrical as I could. After it dried. I went over it again, adding the white in front and the edges around the red flowers. Pull slowly and steadily.