To begin with, make a 9 1/2 inch wonky star block. ( tutorial here ). The tutorial in the link is for a smaller block but the principle remains the same. This is made with nine x 3.5 inch squares, 8 low volume squares and one brightly coloured 3.5 inch square.
Use brightly coloured scraps to make the star points as in the tutorial above and then join the nine patch together.
This then makes a 9.5 inch block. Make this up to a 12.5 inch square by tilting it to one side and adding wedges to each side.
Sew the wedge on and using a 12.5 inch ruler cut the edge off straight, making it slightly bigger than needed to allow a little leeway.
Carry on round and add wedges to each side.
Add the final wedge and then trim to 12.5 inches
I'm intending to make this quilt for Siblings Together. I think it will make a perfect quilt for a child.