I need to turn the nozzle of a rocket engine...

here is a picture...

http://www.stevepinker.com/North-Ame...9081&k=Bbmvkvg

or

http://tinyurl.com/kbwbk2g


It is going to be about 3" diameter and 4" long. It won't be
incredibly detailed but the ribs should show. It will be
hollowed out a bit but the wall thickness will be much greater
than the picture. I need a wood that will turn easy without
tear out and should be cheap. The grain is not important as
it will be painted. Any recommendations?