Can't shell an object

Hello,

I'm having real troubles with this... Does anyone know how to shell this (attachment) so that it looks like this:

I could shell that side fine (picture), but when I tried the other side (approx. 10hrs of trying now) I couldn't... I have attached the side

and would massively appreciate and be sooo thankful if anyone could show me how to shell it (0.1mm),

Thank you greatly!

Ollie Banks

SolidworksParts And Features