Hi Carlos

that is easily solved to define a specific layer. I use a script for construction help lines that i hide and unhide when needed. (in the below they are called "konstruktion")
the script simply create a new style called konstruktion (or reuse the existing one) and attach the konstruktion style to selected lines and the hide them. When you need the lines again you just hit the shortcut again to unhide them.

if you need a layer for 2d drawing lines you just create a new shortcut (like D) with the script below where you have rename Konstruktion to 2Ddrawing. When you have run "make2D" or "make2Dview" you just hit D and you have you 2D lines separated.

script: /* Hide selected objects, and assign to style = Konstruktion */ var gd = moi.geometryDatabase; var styles = gd.getObjectStyles(); var si = -1; for ( var i = 0; i < styles.length; ++i ) { if ( styles.item(i).name.search( /Konstruktion/i ) != -1 ) si = i; } if ( si == -1 ) { var style = gd.addStyle(); style.name = 'Konstruktion'; si = style.index; } var objects = gd.getSelectedObjects(); objects.setProperty( 'styleIndex', si ); objects.setProperty( 'Konstruktion', true );objects.setProperty( 'hidden', true )

//Hep