Looks as though they have mage a block with partial seams as each square has 4 different colours around it
http://learnhowtoquilt.com/quilt-tut...partial-seams/, it looks as though the centre square is around 5" and maybe try your strips at around 2 1/2 " and then you need to get a square template (similar to how you would use and x blocks template
http://www.kiwiquilts.co.nz/site/kiw...20Oct%2008.pdf ) to cut your wonky square.
I would have a play and see how you go.