I am so happy with how these shelves turned out! They’re under $30 from Amazon and hold a surprising amount of products. Totally customizable, too, with the height and it comes with a towel bar attachment (we added that after this). Comes in a bunch of colors, too! Tagging some other styles I looked at, too

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Commissionable links
Shario White Floating Shelves - Set of 2, Wall Mounted Hanging Shelves with Golden Towel Rack, De... | Amazon (US)
OlarHike Black Floating Shelves Set of 4 for Bedroom, Wall Shelves for Bathroom Kids Book Storage, Wall Mounted Rustic Wood Shelving for Living Room, Hanging Shelf for Kitchen Laundry Room Office | Amazon (US)
BAYKA Floating Shelves for Bedroom Decor, Rustic Wood Wall Shelves for Living Room Wall Mounted, Hanging Shelving for Bathroom, Laundry Room, Small Shelf for Plants, Books(Brown,Set of 3) | Amazon (US)
17"" x 7.9"" Floating Industrial Wood Wall Shelf with Metal Towel Bar Black - Danya B. | Target
33"" Round Metal and Wood Hanging Wall Shelf Brown - American Art Decor | Target
Honey-Can-Do Wall Mounted Bathroom Shelf with Towel Bar and Oval Top Tray, White SHF-09519 White | Amazon (US)
Honey-Can-Do Steel Bathroom Slatted Shelf with Towel Bar Gray | Target