Is there a way to have filled or coloured regions in a polarplot?

Is there some way to shade in the region between the red and blue curves?

implicitplot([y = (1/5)*x^2+5, y = (1/20)*(x-5)*(x+3)*(x-10)+30, x = 2, x = 10], x = 0 .. 12, y = 0 .. 40, color = [red, blue, black, black], thickness = 3)

I tried this, but it doesn't seem to like having the x's and y's in the z range. 

 implicitplot3d(x = 6, x = 1 .. 7, y = 2 .. 5, z = 0 .. (1/4)*(x-4)^2+(1/5)*(y-3)^2+10
  , view = [0 .. 8, 0 .. 8, 0 .. 20], transparency = .5, style = hidden);
%;
Error, (in plots/iplot3d/implicit3d) bad range arguments x = 1 .. 7, y = 2 .. 5, z = 0 .. (1/4)*(x-4)^2+(1/5)*(y-3)^2+10

I'm trying to plot a surface above the xy plane that looks like a solid,...

That is, something that will plot a bunch of rectangular boxes in 3d, instead of a bunch of rectangles in 2d.  Thank you.

How can I make the 3d plot of a function such as z = 4x^2 - y^2 so that only the part of the surface above the unit circle in the xy plane is shown?