Made of math
I lived close enough to the old Scottish Rite in Tacoma that I could watch it being demolished from my kitchen window. I loved this building, this big art-deco modernist concrete cube. I photographed it, made a painting of it, and two years ago I started trying to create a digital illustration using a tool called Sketch. I forgot about this image for years, found it, and finally finished over the weekend.
Sketch is a "vector drawing" app mostly used for creating user interface designs for software and the web. It is not for this. "Vector drawing" means drawing with geometry. The app provides easy rectangles, eclipses, and polygons. If you want to get fancy you can draw freehand shapes with a bezier curve tool. Each shape can be filled with a solid color, a gradient, or a pattern.
Imagine cut-out paper shapes, but digital.
There's something very Platonically appealing about making an image this way. It is nearly impossible to fuss with anything but the most critical details. There is no artful scribble that can imply grass or leaves. You have to think in big, flat shapes.