can anyone tell me or show me if possible what a back to front shell is for piping i keep reading that people cant do them but what are they

Can you post a link to what you are reading so we can better understand?

I assume you're talking about a back to front shell border, right?

If people can't do them, I'd assume you won't get many responses telling or showing how, but I'm up for the challenge if you can supply more information about what you're looking for.

I'm still up for the challenge and would like to show you if you'd respond.