I have noticed more retail stores lately with customized unique door handles.
For example, REI has a climibing axe handle. Dunkin Donuts had handles made of the letter “D.” See photos below.
I predict that this is a new wave of non-traditional trademarks. Look for more stores to use such custom handles to mark and accessorize their brand. And look for more trademark applications featuring such handles. In the USPTO records, I could find just one, from The Gelateria Ice Cream. Dessert. Lounge, Inc.:
Related post: A new slogan: THE NONTRADITIONAL TRADEMARK LAWYERS