dKip1,
I don't know how to set a global property for error bar end caps. However, JSL or scripting can make tedious customization easier. Below is a simple example. JSL can also be used to create an Application or an Add-in that prompts for X, Y, Color etc. variables and applies the favored customizations. In other words, it works as a front-end to getting the inputs and applies the customizations.
Names Default To Here( 1 );
Open( "$SAMPLE_DATA/Big Class.jmp" );
obj = Graph Builder(
Variables( X( :age ), Y( :weight ), Color (:age) ),
Elements( Bar( X, Y , Legend(5), Error Interval ("Standard Deviation") ) )
);
frame = Report( obj )[FrameBox( 1 )]; //get a handle for the graph FrameBox
seg = (frame << XPath("//BarSeg")); //get a handle for the bars
//--- can customize all at once ---/
seg << {Error Bar Cap( "Tiny"), Line Color( "Medium Dark Gray"), Line Width( 2 ) } ;
//--- can customize (set properties) individually ---/
//seg << Set Error Bar Cap( "Tiny");
//seg << Set Line Color( "Medium Dark Gray");
//seg << Set Line Width( 2 ) ;