This was a long process, so I will explain each step.
1. I lightly rough sketched the picture.
2. I finished the rough sketch.
3. I inked the rough sketch and finalized the lines.
4. I cut out each paper airplane and each person from the drawing.
5. I painted a gradient of sky colors on a canvas. This would be the background to the paper airplanes.
6. I placed all the cutouts on the canvas and I secured them with photographic mounting tape. The tape is like double sticky foam, so the paper airplanes are 3-D and they stick out.