You will need: 6”x 8” rigid paper(card stock), cutter, floss, pencil and ruler Connect opposite corners with diagonal lines, this finds the center point. Find 4” between diagonals, keeping the ruler parallel with the edge of the paper and mark points. Do the same to the top line, keep it parallel! Then connect the dots with a line completely across. Next we will be making the vertical lines by connecting the same dots to complete the rectangle.￼ 3” x 4” as an aspect ratio is 3:4. This ratio when we scale up will give 6” x 8” or 18” x 24”. Carefully cut the window out. Use a safe surface if using an exacto. Within the top 4” edge, mark out every inch, making 3 marks. Mark inches for each side all the way around. 2 marks on the 3” vertical sides, 3 on the horizontal Go around and cut notches on every mark that you just made, they only need to be a little cuts.￼ String the floss between and across notches and use tape to secure it when needed.￼￼ I have looped the floss over to the next notch and kept it running. Finish the grid and when you are done you should have a gridded viewfinder with a 3:4 aspect ratio. There you go, a gridded viewfinder!