To "fill in" the space between two curves (in this example, f(x) = sin(x)-2 and g(x) = 3-x^2) do the following:[br][list=1][br][*]Define your two functions.[br][*]Use the SURFACE command: Surface[ t , u f(t) + (1 - u) g(t) , 0 , t , x(A) , x(B) , u , 0 , 1 ][br][/list][br][br]Once you do this, you should be able to change f(x) and g(x) and the surface should update accordingly!