\usepackage {pstcol}
\begin{pspicture}(0,0)(2,2)\showgrid
\pscustom[fillstyle=solid,
    fillcolor=gray]{%
 \pscurve(0,.5)(1,1.5)(.9,1)
 \pscurve[liftpen=1](2,.5)(1,.1)(0,.1)
}
\end{pspicture}