I like experimenting with multiple canvases. I've done many diptych, triptych, and even quadtych paintings. This is the same floral reference photo I used for Poppy Quadtych posted a couple weeks ago.
If you look carefully, each flower is outlined in yellow-gold. I left a white boarder around each flower, then the final step was to paint the boarder with quinacridone gold acrylic paint (Golden brand.) I love that tube of q. gold. It'l like sunshine in a tube. It's so transparent, it only shows on the white areas.