Patterned line width variable while pattern size also is relative to line width

Hi I am looking to make a variable patterned line width, such as these tentacles, but I need the tentacles to be proportionate to the width of the line size.  Right now, the tentacles turn from circle to oval as the line width decreases.  Need them to remain circles.  IS there anyways to do this?

https://www.youtube.com/watch?v=S_1hwdkKWFc&lc=UgzfqYfzXx7or9pwU-x4AaABAg.9ywUSf6uWZF9ywVVggOGkM