Please post an image and an Skp (save as V6) of what do you want!
A text is very poor for describe something! 😄
And for a no native language that is a nightmare! 😄
A profile is 2D a Cylinder is 3D ... ???
And modelize something is time losted for helpers! 😉
When you edit a Component (Assemblies or not) seems there is no problem ?
GIF_cylinder.gif
https://i.postimg.cc/FzgQ2pTb/v6.jpg