How to copy a brushstroke from one frame, and then pasting it on the next frame

Hi there, a better solution for you, rather than pasting the brush stroke, would be to paint with the Brush set to "Continuous". This will leave the paint stroke on for the duration of the animation. Then you can keyframe the Brush stroke's Path value to animate between shapes. To do this, draw the stroke, keyframe Brush Path property, move to where it changes, re-draw the path with the Path property selected. This will redraw the path, creating a new keyframe. The brush stroke will animate between the two values.

I recommend starting by doing the start point and end point, then go to half way between these two points and redraw it again. Keep going half way between the KFs till you have the animation following the correct movement. This way you can achieve what you need with the minimum amount of keyframes.

This tutorial may be of help to you;

https://www.youtube.com/edit?o=U&video_id=rl6WITnMgwM

You can copy paste the brush strokes in After Effects. Select the layer you have made the brush stokes on and than press P twice (PP), to reveal the paint properties & brush Strokes for the layer...Select the Brush Stroke and than use the copy command and than select  another layer to paste the brush stroke.

Note - If you want to copy & paste the brush strokes into the same layer then shortcut for copy & paste wont work for that you need use the duplicate shortcut which is (Ctrl + D) or (CMD+D).

Screenshot for Reference -

Have you tried typing Paint in the search help field and checking out the community resources and help files? There is actually quite a bit of information on how to use the tool. There is a link to an article by Chris and Trish Meyers right there that explains how to use the tools. You can set the duration of a stroke in the timeline. The controls are pretty hard to find by just poking around. Sorry I don't have time to pull a screenshot for you.