Best backdrop material ever used (where purchased) and would use again on that next layout? What would you not use and why. Your best technique.
I would have to say that my best (and only) “backdrop” is a waterfall. Rocks; courtesy of Mother Nature: Water; courtesy of mother nature and delivered by the city.
But, then again, you are probably talking about those smaller scales that do not use real rocks, they do not use real water, they do not use real sunlight, they do not use real dirt, they do not use real plants.
Come to think of it those smaller scales do not use anything that is real. Its all an illusion.