I've been wanting to start a growth chart for Luke (and eventually Elsie too). I love just writing them on the door jams - I had my height tracked on my bedroom door jam growing up (I think I did that myself), and it was great...until we sold our home and the door stayed with it.
Since we're still just renting this house, I need a portable solution...that still looks good hanging around the house since it's not "hidden" in the door jam. And I'm not super into those cutesy little charts that your child will outgrow (as decor) as they get older and cooler. Sooooo, we did this.
I bought an extra board when we were buying the materials to build our kitchen table and stained it the same color (but just one coat). I measured the lines, hand made some stencils, and used a sharpie to draw the numbers on. Super quick and really easy. I hung it on the wall with those 3M velcro hanging strips so I can move it around the house if I want without worrying about nail holes annnnd it can easily travel from home to home.