bepsf You don't purchase it as wainscoting - it's purchased as plain MDF panels and various moldings that are cut and applied to the wall, then painted...
...and it all comes from a typical lumberyard.
The walls in this bathroom are covered in a mural, so there's less need for additional art. The simple branches and flowers wrapped around the corners cause your eye to flow around the room making the space feel larger. Tip: When working in a smaller room, considering decorative elements that move the eye around the room. This might some wall treatment, horizontally oriented artwork or well-structured vignettes scattered about.
Here’s another example, with wallpaper rather than a mural. The whimsical nature of the wallpaper paired with the exactitude of wainscoting is the perfect combination of modern meets traditional.
This photo gives me an idea of how white wainscotting would look in our powder room, with dark hardwood floors, and a dark vanity. Kin of interesting. Study this photo.
...and it all comes from a typical lumberyard.