My wife commissioned me to make some floating shelves for our bathroom. We saw examples online where floating shelves were made from an interior door. In the examples I found, they were painted. My shelves are similar, but I wanted to maintain a consistent wood grain all around, which then got a pretty dark ebony stain.
I started with a used interior door with wood veneer in good condition from the Habitat for Humanity ReStore. I cut out some pieces to the sizes I needed, then removed the corregated paper core from the inside:
Alternatively, you could use a regular stacked dado set like this:
Then I cut a 45 degree bevel in the edges as well as in the pieces I cut for the inlay:
Sorry, I didn't photograph the finishing. I applied an ebony stain (maybe a few times) and then sprayed on a couple of clear coats to make it durable enough for use in the bathroom.
As always, if you have suggestions for better ways, please share in the comments.