Im not sure ....are you asking about a floating art ledge?
Here is a link that might be helpful.
If you want a floating frame for a canvas, here is a good step by step tutorial. https://www.hgtv.com/shows/room-lab/diys/how-to-make-a-modern-floating-picture-frame
Are you talking about something like this. https://lifeonsummerhill.com/free-fall-pumpkin-printable-and-diy-wall-hanging/