Gap between line segments

Question

How do I set two line segments apart (at suppose 12%) of it's length no matter how large or small i resize the two line segments, sort of like the settings in ChemBioDraw 13.0 for anyone who have used this software ? For anyone with experience in ChemBioDraw 13.0 you can look into the draw settings and it will say how far apart the two lines in the double bond is, line width etc..etc.. Any ideas ? Thanks !

Answer 1

ghostanime,
When you use Effect>Distort & Transform>Transform>Move a copy, you still have just one line with a copy line at a certain horizontal distance from it, and that line will disappear if you click Reduce to Basic Appearance in ther Appearance palette/panel, and misbehave if you rotate; also, the original line will be what you are moving.
When you Object>Expand Appearance, you will have two independent lines/objects instead.
You may select and Group ((Ctrl/Cmd+G) whatever you wish to reuse, then copy and reuse as a unit, or even turn it into a Symbol.
With the suggestion of using an Art Brush, you actually create such a unit for the double bond itself; I suggested that because you mentioned the wish to keep the proportions. You could also create the two lines as desired and group them; you should be aware that If you wish to change the size, you will have to tick Scale Strokes & Effects if you wish to keep all the proportions.
Groups can form part of groups, so you can assemble building blocks (such as double bonds) into more complex bonds (such as molecules).
Made as an Art Brush or as a Group, when you select the double bond, you will operate it by the centre between the two lines (presuming you have the Centre Reference Point selected in the Transform palette/Panel), with the effect you will operate it by the centre of the original path, which will be off.