What you will need for this Instructable:
Hand Sanding Block
Letter and Number Hand Stamps
Step 1: Select Your Wood
This is a highly personal choice. I picked a piece of Claro Walnut that was sourced locally in California because my son was born in Berkeley. Its dimensions are roughly 1"x12"x6'.
Step 2: Square Your Edges and Remove Mill Marks
I ran the edges of my walnut on a Martin Joiner to clean them up. Set to 3/32" it only took about 6 passes per side. This will vary based on the board you're using.
Step 3: Sand, Sand, and Then Sand Some More
I sanded all edges and then both sides. I worked my way from 80-320 grit sand paper on a radial sander. A crucial component whenever sanding is to be sure that you've rigorously sanded with your rough grits before working your way up to the finer grits. For my board it took about 2.5 hours.
Step 4: Break the Edges
There are several methods for going about this, but I wanted a light break to the edges. Therefore, I simply used a hand sanding block and the same grits that I used with the radial sander.
Step 5: Clean the Wood
Once all sanding is complete use pressurized air to blow off any saw dust. This helps in the finishing steps.
Step 6: Oil the Wood
There are many different finishes that could be chosen for walnut. I wanted to keep it simple so I went with mineral oil. Simply apply a small amount to a rag and rub on. It is extremely tempting to dump this stuff on but try not to so that you are able to achieve an even, light coat.
Step 7: Hand Stamp
I decided to customize this growth stick specifically for my son by putting his name and date of birth at the bottom. Simply select the numbers and letters you want to use and then give a medium tap from your hammer to deboss into the wood. Try to get it right the first time as a second swing rarely works.
Step 8: Repeat Steps As Necissary
The preceding steps can be repeated in order to get a richer finish. Personally, I only gave it one pass to try and maintain a more rugged aesthetic.
Step 9: Final Thoughts
This project was very fun and I can't wait to begin marking my son's height on it. I will continue to use the hand stamp tools to do so to give it a consistent look. Re-oiling varies based on climate. Here in the Bay Area I reoil our walnut every 6 months or so.