In a cabinet shop the board stretcher is always a good one. Or while doing counter tops, the laminate stretcher. I had a new guy looking for 45 minutes one day for that one.
Aluminum putty....we work on an all composite airplane.
The RAT (Ram Air Turbine), which is used to power systems in the event the engines both fail, is a big propeller that springs down under the belly to power a generator and hydraulic pump. We get new guys thinking it's an outboard motor in case of water landings.
When a supplied fastener length is too short for the stack-up we're fastening, sending the new guy to the tool room for a bolt stretcher is always good for a laugh.