I want to create a panel in revit as a perforated shading device,with pattern similar to the leaf structure, something like on this picture.( only this big elements without this smaller fillings)
Is there something already available or maybe someone can give me a hand ho to bit that ?
You could use the Voronoi Node. This works given a face of a surface and a list of UV coordinates from that surface, you will need to randomise the UVs on the surface. For the texture, which is another Voronoi, you probably want to google Voronoi alpha texture and use that for a cut-out effect in your surface material. See below for an example of using materials to give you what you are after.
You may also look here Voronoi: How to Offset, Fillet Cells? we have recently discussed.