Placing the panels on the floor helps me look at the piece in its entirety, plus gives me easy access to draw the beginning shapes in. For the drawing, I use oil sticks which resemble a large piece of chalk full of oil paint. As I work I'm considering continuity from one panel to the next, and repeating geometric elements of different sizes. That garbage can top gives me a perfect small circle, and an outdoor table top made making the large circles easy. For me, a successful triptych means that each panel works as a single composition, and the three pieces together form an interesting composition as well.