This is a way cool idea. So, you have treated plywood under them and 2x 4's split on the sides and then painted over and sealed? You don't think the wood will deteriorate or get termites or some such? Just nosy here. It is such a cute idea. I have seen this done, but forgot about it over the years. How about a few stepping stones around your gardens fellow quilters? I have a round one, painted with patio paint in a hummingbird pattern that I use for the marker for a deceased kitty cat. It has held up well now for 3 years in our back yard.
But, your idea has me thinking square stepping stones. Thanks!!