Shell tool question

[Lue]

I made 3 sketches.But only the circle could work under shell tool. Any constraints on tool application?

[Koko_Shapr3D]

You should try it with a smaller thickness. It works for me:

By the way, you can check the maximum possible thickness with the offset tool (you can drag the edge until the maximum allowed thickness is reached):

[Lue]

Thank you for fast reply.