Damn. That’s a nice box build. Do you like using the hardwood rather than mdf? I’ve only used mdf so not sure how they differ in sound and durability. I can say that coating that box is guaranteed easier than mdf. Lol
Baltic Birch. It's more expensive than MDF, also lighter than MDF. Cutting the birch can be tricky because it splits on the edge of the wood if a tablesaw doesn't have more teeth per inch on a blade vs a reg table saw blade. There should be no sound difference between woods. I have heard people talk about this before and it's a myth. Single m3 8 8" driver being used.
Enclosure finish compromises of English Chestnut stain from local hardware store and applied with clear coat about 4-5 times. Clearcoat really brings out the woodgrain and finish of the wood. Otherwise, stain alone w/o a clearcoat will look just dull. It took quite a while to get it where it is now. It's easy, just time consuming. Everyday I was working on it. But only a few hours or so at a time.