These are pieces of wood from the hardware store. The space between each one expands by four inches at each interval starting from the right and getting larger to the left. The first two are four inches apart, the second two eight inches, the third twelve inches and so on.
Looking back the four inch spacing was too small. Maybe a foot difference instead of four inches would work.
If I were to do it again I’d also like to have some type of light at the top of each stick so the space would also be delineated at night.