To create a super slim dubbed body on a fly wrap back to the start of the bend with your tying thread then forward a little ways up the shank. Establish a thin dubbing noodle on your thread, I’m actually making this one a bit thicker and longer than needed to prove a point.
Anyway, take wraps with the noodle so the dubbing starts right at the back end of what will be the body. Make sure to get a full turn of dubbing around the hook shank. Give your bobbin a really good clockwise spin to cord up the thread and the dubbing. While holding the thread in your left hand, bring your bobbin up with your right and anchor your tying thread on the hook shank where the front end of the body will be. Then snip the dubbing noodle end of the thread off close. With hackle pliers, get hold of the bottom end of the dubbing noodle and the thread. Then snip the excess thread off close.
Begin twisting the hackle pliers clockwise which will continue cording up the thread and the dubbing. Start taking wraps with the tightened dubbing noodle, twisting it clockwise as you go. When you reach your tying thread, use it to secure the noodle, then snip the excess off close.
Not only does this make for a very slim somewhat segmented body, it also allows you to have the perfect length of body because the excess dubbing noodle can always be snipped off.