I created a simple vignette for my coffee table, but I use the exact same ideas for shelves, tiered trays, dressers, entryways, etc.
If I wanted more on my tray, I would add another small group of 3, or add a group to each end to make 5 groups.
So if I was going to create an open shelves display, I would create 3 groups of 3 across my shelves.
As you can see I just add and group MORE smaller vignettes together to create a larger shelf or tiered tray display.