Here is our version:
I took a piece of lumber that my husband had saved from a burn pile. Then, I took a small amount of barn paint and diluted it with water so it would have the "white-washed" effect and painted all sides of the board. Next, I used a Sharpie to draw on the numbers and lines. Finally, I added the hieghts of Ruthie at age 1, 2 and 3 and Asher at age 1.