I tried to rebuild one of the World Trade Center towers.* All the material to make an outer shell had been salvaged and was sitting in a large stack. A woman I know from the art world was in charge of the rebuilding; her father built the original and I kept hearing how stern, demanding, and scary he was. I started laying out the planks on the floor and cementing them together. They had to go down in a particular order and I removed quite a few planks from the stack before realizing I'd messed up the order. Somehow I had it in my mind that this was the floor covering and I was assembling the odd-sized rectangular planks like a jigsaw puzzle. My female acquaintance came in, saw what I had done and said, "This material is for the walls, not the floor, the floor will be polished black marble. My dad is going to be so mad, pull these up, hurry!" Fortunately the cement between planks hadn't completely dried, so I was able to pry up all the planks. I put them back on the stack, hoping no one would notice the order was messed up.
*This isn't as narcissistic as it sounds. I see the WTC construction site regularly from the subway that goes into the pit.