3) Using your ruler, draw a diagonal line across the uppermost square, from its top right corner to its bottom left corner. Scribble out the upper left half (now a triangle) of the square, as you won’t be using that part.
Next, draw a diagonal line across the bottom right square, from its top right corner to its bottom left corner. Scribble out the lower right half (now a triangle) of this square.
4) Cut out all parts of the entire shape that have not been scribbled out. This should be a square with two triangles attached to it, one on the top and one on the right. This is your template.
5) Trace your template onto your pretty piece of cardstock (or onto the plain piece of cardstock that you intend to decorate), and cut the shape out.
6) Using your ruler and the tip of your mechanical pencil with no lead showing, score a line (make an indent) along the edges of the square that connect to the two triangles.
6.5) [optional] Cut a square of pretty paper slightly smaller than the one you used for your template and glue it onto the square portion of your shape. I generally do this if the paper I’m using is quite plain.
7) Fold one triangle inwards, so it covers the upper half of the square.
8) Apply glue to the underside (the side still facing up) of the second triangle, and fold it over onto the first triangle.
8.5) [optional] As in step 6.5, if you’ve used plain cardstock and want to glue fancy paper on top of it, cut out a triangle of the fancy paper that’s slightly smaller than the folded-over triangles of the bookmark. Glue the smaller triangle on top of the larger, folded-over ones.
9) Add any decorations or illustrations you wish. Use by slipping over the corner of the page you wish to mark, like a pocket.