A giant pane of glass that was custom made to protect a giant wooden conference table. The glass wasn’t heavy, but it really sucked turning a corner with it in a tight stairwell, flexing it too much, and then having to clean up a million pieces of broken glass.
I’ve also moved a lot of logs. It sux.
I know when I have a very real intelligence breakthrough like this I make sure to do a press release so my enemy knows they have to fix that particular weakness.