Pottz; Most grow out of simple shapes twisted 30 or 60 degrees out of true. Squares, diamonds triangles etc. Then I add my design elements and a whole new shape evolves. By determining the direction of "light" falling on the drawing the different species are applied to give the illusion of 3D. Some are common shapes from across the internet. A form of the tree for example has been produced by innumerable woodworkers over the past few years. I took it and re-drew the shape to work to my benefit then putting into play those aforementioned elements its presentation is now entirely different and unique.
Some of my most creative moments have been when I've had to cover up an error in my woodworking.