Make a British Flag from Scratch
Below are illustrations to show the process I took to build the flag. By the way, I used Photoshop for this.
First I started out with a blue background [fig 1]. Next I created the red cross [fig 2] which are two rectangles, one vertical, one horizontal. Then I added the white borders to the red cross [fig 3]. Next, [fig 4] I added the thick white diagonal bars followed by [fig 5] layering the smaller red diagonals on top of the white diagonals, while making sure the white borders from fig 3 overlapped those (see fig 6). Finally, I added a wavy texture and some shadows to make it feel more 3-D [fig 7].
Fig 1
Fig 5
Fig 2
Fig 6
Fig 3
Fig 7
Fig 4