I am using mineral oil to seal the wood. I’m also using a stain than can be light to dark gray. It is made by soaking steel wool in vinegar. To attach the nuts hatches, I’m using dowels and glue. This glue is made by cooking milk powder with vinegar to get curds, these are drained, rinsed and combined with baking soda and some water to get the preferred thickness.
It is supposed to be waterproof. Wisconsin weather will test that claim.;