how to create shell in this model?

this is the tutorial example in solidworks. Even though i followed the instructions I am unable to create shell with the thickness of 3 mm . can anyone help with this?

2 Answers

The first solid feature in your model, Revolve-Thin1, shouldn't be a 'thin' feature.

Due to the 'thin' feature, your model is already sort of shelled, that is to say, it is hollow, and this hollowness is not allowing the shell command to work.

Robert's got the right answer. I'm just adding an image to show the difference between your model and the tutorial.

Your model has a centerline running it's length, this is causing the Thin Feature Robert mentions.
The tutorial has a line (not a centerline). That allows the sketch to be "closed", and allows the Revolve feature to make a solid.