Star envelope

Here is a very simple technique for folding an envelope from a sheet of paper. The first and third folds have no reference points, so you can move them depending on whether or not you want the star to sit in the centre of the envelope. It can be folded from an A4 sheet, as in the video, but it also works with rectangles of other sizes or with a square. You can add a sticker to seal it if you like.