Non-rotating end caps to strokes

Thanks, Kurt, I should have remembered that conversation, as much as I was dazzled, as always, by your solution.

Peter

Kurt: I wasted far more time failing to find search terms that would locate your solutions than it finally took me to work it out myself! : )

Scooby-Dooku:

My method: Use multiple strokes for the main body of the path; you could use a brush if you like. Turn a rounded rectangle into a Scatter Brush, with the spacing set to a ridiculously large value so that only one instance of it would show up on any reasonable-length line,  and set rotation relative to the page. Apply that to a third (top) stroke. As Kurt suggested, save this as a Graphic Style and apply as needed.

I'm not sure exactly how you want to use lower opacity, but you can lower the opacity of the whole path or just the bottom couple of strokes without showing overlap. To lower the opacity of just the oval, as I did at the bottom of the illustration, I duplicated the oval stroke, set the opacity of the lower one (directly beneath the top oval) to 0%, and set the other strokes to Knockout Group. Then set the top oval stroke to whatever value you want. You can, of course, save multiple Graphic Styles to suit your needs,

Peter

You can do that with a graphic style based on brushes.

There were some similar requests in the past and I provided some possible ways a couple of times.

You may do a forum search to find them.

Scoopy-Dooku,

Instead of brushes you can simply apply two Strokes to the line path in the Appearance palette (darker small Stroke Weight on top of paler large Stroke Weight).

As a separate end cap you can simply use a horizontal rounded rectangle (instead of an arrowhead) on top of the path, centred over the end of the path;

If you wish to move both at the same time, you can deselect everything and simply ClickDrag over the whole rounded rectangle with the Direct Selection Tool, thus including the end Anchor Point of the line path /avoid other Anchor Points on the line path, and then ClickDrag by the centre/end to reach the desired spot. You can have them Grouped.

Or you can position the (end Anchor Point of the) path first, and then simply ClickDrag the rounded rectangle with the (normal) Selection Tool by its centre (you can set use Show Center in the Attibutes palette if needed) to snap to the end Anchor Point of the path. Smart Guides are your friends, saying anchor when you are within snapping diastance.

This will give you the horizontal end cap positioned accurately.