union two or more layers without duplication?

[rich2005]

Well you can mess around with merging selections forevermore,  if you want, or as here I blanked out overlapping sections using layer masks.



or you can make a repeating pattern as attached. Which I think is favourite.

https://www.dropbox.com/s/4jrkgj0ei8egpk...n.png?dl=0 1.7 MB