I had a moment of Maths yesterday and thought of you both - Do you know of a Crinkle Crankle wall? It has a wave pattern but uses less bricks than a straight line because the stability of the curve means it doesn't need to be as thick and doesn't require intermittent pillars. My family were not that interested to know this! but having "moments of maths" as part of thinking about our day is proving useful. .. I didn't think of it at the time , but getting bricks to form a curve is a bit like the bitpaper trying to fill a circle with cuisenaire rods.