\begin{tikzpicture}
	\draw (0,0) arc (-180:0:.5cm);
	\draw (2,1) arc (-180:0:.5cm);
	
	\draw (0,0)--(0,4);
	\draw (1,0)--(1,1);
	
\begin{pgfonlayer}{background}		
	\draw (1,1)--(2,2);
	\draw (1,2)--(2,3);
	\draw (1,3)--(2,4);

	\draw[line width=6pt,white,opaque] (1.9,1.1)--(1.1,1.9);
	\draw[line width=6pt,white,opaque] (1.9,2.1)--(1.1,2.9);
	\draw[line width=6pt,white,opaque] (1.9,3.1)--(1.1,3.9);
	
	\draw (2,1)--(1,2);
	\draw (2,2)--(1,3);
	\draw (2,3)--(1,4);
\end{pgfonlayer}

	\draw (2,4)--(2,5);
	\draw (3,1)--(3,5);
	
	\draw (0,4) arc (180:0:.5cm);
	\draw (2,5) arc (180:0:.5cm);
\end{tikzpicture}