This was what I provided for Freem009 on a 10mm grid and they just rounded the corners. 
 

So we could use a grid in a similar way like the yellow line?

Ok this should be the first draft, PLEASE DON’T BUILD TO IT YET, it’s purely a discussion document based on this thread so far.

It’s based on the RSTower groups HO Freemo and I’ve adapted it to use in my Freem009 and BonsaiRhB standards which you can find in my signature. 

ok correct version now attached  

RhB Nm9 standard v1.pdf