Refresh my memory, please...

I remember a mod (not Adv Duplicator) where you would copy a prop, and before pasting it, you could have it be in line or perpendicular or something to the prop along a grid by editing where on the three axes it was, thereby making walls and ceilings from a single prop in seconds instead of hours. But I don’t have it downloaded or installed anymore and I forgot what it was called.

Stacker STool.