Hi Jean-Paul, yeah you will normally want to use Offset or Shell for things that have constant thickness.

The surface offset mechanism seems to be having a problem with your rounded tip part in this case, so that is making things a bit more complicated here.

Normally what you would want to do would be trim those panels but keep the surface fragment on the inside of the panel instead of throwing those away. Then you would use Shell to thicken that fragment into a solid of even thickness, then delete the outside surface of the shell and then join it to the outside part. But there seems to be a bug preventing the offset or shell from working on your revolved surface there. I'll try to take a look at what is going on with that.

- Michael