Almost floating shelf!
Small rooms have it that every square centimeter is worth its weight in gold, and even platinum, when it comes to storage space. Therefore, the ostentatiously impractical shelf in decoupage had to be forgotten.
Shelf Floating Theory and Design
Floating shelves are those with hidden brackets. The metal or wooden frame supporting the shelf is located inside it. I had an idea to make something similar, but the brackets will be attached to the cupboard on one side and to the wall on the other. A shelf will fill the space between them. Of course, the phrase "I had an idea" is abused, because such shelves have been used in cupboards and pantries for centuries, etc.
Due to the fact that I only had 9 mm plywood, and I wanted the shelf to look more massive, I added a pine scantlings edge to the front. It will also act as a shelf stiffener.
The brackets were also made of wooden slats, matched so that their thickness + the thickness of the plywood equal the thickness of the front square timber.