As an artist sometimes I look at the lightweight cardboard divider from a box of tea bags and a handful of brightly colored foil candy wrappers and see a bookmark.
Any fancy foil, paper or ribbon scraps would work just as well. I simply arranged the candy wrappers till I came up with a pleasing pattern, then taped them to the cardboard base. All I had at the time was tape, glue would work just as well if you have it on hand. Simple as that. No rules, no right or wrong, no complicated instructions. This is what I came up with.
Have fun making your own bookmark!