\def\ll{100pt}
\def\dl{2pt}
\def\dr{4pt}
%
% Same width and borders
%
\def\w{2pt}
\setbox0=\hbox{%
\cals@rs@sofar@reset
\cals@rs@sofar@next\ll\dl\dr\w
\cals@rs@sofar@over\ll\dl\dr\w
\cals@rs@sofar@end
}
\showbox0

%
% Same width, bigger borders
%
\setbox0=\hbox{%
\cals@rs@sofar@reset
\cals@rs@sofar@next\ll\dl\dr\w
\def\dlII{6pt}%
\def\drII{8pt}%
\cals@rs@sofar@over\ll\dlII\drII\w
\cals@rs@sofar@end
}
\showbox0

%
% Different widths
%
\setbox0=\hbox{%
\cals@rs@sofar@reset
\cals@rs@sofar@next\ll\dl\dr\w
\def\wII{4pt}%
\cals@rs@sofar@over\ll\dl\dr\wII
\cals@rs@sofar@end
}
\showbox0

%
% Different widths, second is 0pt
%
\setbox0=\hbox{%
\cals@rs@sofar@reset
\cals@rs@sofar@next\ll\dl\dr\w
\def\wII{0pt}%
\cals@rs@sofar@over\ll\dl\dr\wII
\cals@rs@sofar@end
}
\showbox0
