\documentclass{article}% Herbert Voss bsp346.tex
\usepackage{pstricks}%  >= version 1.04
\usepackage{pst-vue3d}%
\pagestyle{empty}%

\begin{document}
  \psset{THETA=30,PHI=0,normaleLongitude=0,normaleLatitude=0,RotY=90}%
% In this pspicture, the cylinder is centered inside the "blade".
\begin{pspicture}(0,0)(5,5)
  \CylindreThreeD[fillstyle=solid,fillcolor=gray,linestyle=none](0,0,0){5}{20}%
  \pscustom[fillstyle=eofill,fillcolor=yellow]{%
    \CircleThreeD(19,0,0){7}%
    \CircleThreeD(19,0,0){12}%
  }
\end{pspicture}\qquad
% In this pspicture, the "blade" should look like it is cutting into 
% the cylinder.
\begin{pspicture}(0,0)(5,5)
  \CylindreThreeD[fillstyle=solid,fillcolor=gray,linestyle=none](0,0,0){5}{19}%
  \pscustom[fillstyle=eofill,fillcolor=yellow]{%
    \CircleThreeD(19,0,-4){7}%
    \CircleThreeD(19,0,-4){12}%
  }
  \CylindreThreeD[fillstyle=solid,fillcolor=gray,linestyle=none](19,0,0){5}{1}%
\end{pspicture}
\end{document}

