Both are insulation foam painted to look like wood. That worked great for the sign, but the post was actually not quite sturdy enough, and broke not long after this photo. Fortunately I was able to set aside the broken bit and just be somewhat more careful with the shorter post, and then I remade the post with a metal core to give it some extra strength and rigidity
Nice! I hope that it works out well for you! Mine is still holding up beautifully