Well I have a 40' by 30' inground pool that is old as heck with very rusty steel walls the liner wash trashed in storms and a section of the wall buckled. The local pool guys recommend tearing out the old was and basically installing a new pool. Cast about $25000. what I'm wondering is how hard and at what kind of cost would it be to DIY cinder block walls and convert it over to a natural pool. Or is this just crazy.