Step 2: The Cardboard Pieces
Get your ruler and pen, and mark 7cm wide and 8cm long, or 2.8 inches by 3.2 inches, and cut it out, repeat 12 times.
If you want to decorate them then this is this time, if you do it later then it's just impractical with the glue or ribbon in the way.
Next is to lay the twelve out in two columns, length ways. Mark the left side so you can tell which side is the top and bottom, and the right side the same but differently, so you can tell which ones are in the left and right column. Flip each on upside down, if you flip it outwards I find it much easier, because when when you get to flip it inwards, it's all in the same position.
Finally is to mark the undersides so when you put the ribbons on, they're all in the right place. Mark 1cm in from both of the 7cm sides, and then half way between. Run a line all the way up. In the pictures I only marked in a bit, but I recommend marking the whole way through.