Yes , u can do anything u want , it's all up to the imagination , if u want curvs instead of corners then u have to make the curve by placing a couple of blocks next to each other to form a curve , there's really no special secret or way to do this other than the one common sense should dictate to u , though if what ur looking for is a way to do it by clicking a button or a diff way of hollowing a block in wed then the answer is there isnt , u have to manually do it , though u CAN make a group of the curved surface and just copy and paste it where u need more curves , so u dont have to manually make each one , it isnt too hard once implemented.