File > Print > Line Thickness
Getting and setting system-level line thicknesses for a printer using
the following enumerators are obsolete and superseded by document-level
enumerators.
IMPORTANT: In SOLIDWORKS 2009
and later, SOLIDWORKS recommends that you set document-level line weights
instead of system-level line weights. However, if you must set system-level
line weights on a document created in SOLIDWORKS 2008 or earlier, then
you must set the system-level line weights before opening the document.