Bricks

The Dude is using a robot to build a brick wall for an architecture
school project. The precision is amazing, yet the robot is very
"dumb" and can't cope if things are out of place by a few
centimeters. This fact was actually somewhat comforting because we
imagined the robot dropping the bricks and coming after us. You can
just barely see the slight lean of the wall if you look closely at the
left edge.