I have recently seen so many lovely ideas for 3d projects that I just had to try these lovely corner bookmarks, there are two different ways to make these bookmarks.
Version 1 uses a 5" square piece of card
Score from corner to corner across the diagonal so that you have four triangles.
Cut out one of the triangles & use as a pattern for the decorative borders & strips.
Fold along the score lines to make a triangle that will fit over the page of your book & decorate.
Glue the two flaps together to strengthen & decorate.