There are many types of sticker sheets with borders, corners, pictures and you name it. Some sticker sheets have designs in the form of a mosaic. If you stick them on a sheet or card and color them, you have a beautiful motif for e.g. a nice card, invitation or in a bullet journal.
I made some examples. They are colored with colored pencils of Faber Castell Polychromos. These are very fine colored pencils, with which you can mix the colors so well. You can make beautiful color transitions with them.
Maybe I gave you a nice idea.