I wanted to have a growth chart that I could use from birth to adulthood for our kids. Many of the ones you can buy only go through 5 ft. tall. Instead I bought a piece of furniture-grade pine trim. It came pre-sanded and I didn't finish it. I bought some decorative wood shapes from Joann's. I glued them to the board as decoration and wrote each child's name at the top. I bought some wooden screw plugs and painted them. I use these to mark their birthdays on the chart.
Once they were hung on the wall I started the chart by measuring out their length at birth. Then throughout each year I measured the kids and marked their height with a pencil and the date. I always measure their them on their birthday too. For those measurements I glue one of the colored wooden plugs onto the chart.