Everybody buys spray nozzles for their garden hose. It seems like I buy a new one every year either by the item breaking or a new nozzle having some cool new feature that I think I need.
Many spray nozzles are designed with the spay button triggered by your index finger. Nestled on the interior of the grip, the trigger is out of the way of accidental actuation when the hose is inevitably drug along the ground.
I purchased a new nozzle from Menards that had a thumb actuated lever on the end of the nozzle. In the store, it appeared like a great design - smooth, easy to move. When I got it home, the design flaw became obvious.
While winding the hose up for storage, the thumb lever contacted the ground and turned the sprayer on. After wrestling a now writhing splashing hose and getting a faceful of water, I thought " Hey. It's an accident. No way it will happen again." Until it did. The next day.
Getting a wet face, and clothes occurred daily until I threw out the new nozzle and went back to my old reliable.
The fundamental issue with the design is whether anyone actually tested the design in real world conditions. With rapid prototyping, functional models could have been built AND tested. Were they?