First project to overcome failure, and prevent my Grandpa from fishing.
When I was in early high school, I had saved the entirety of my consulting money for a while and tried to build a small unmanned submarine.
I set the budget I thought was appropriate (went absolutely all in on it) and I knew that I'd would have to be crafty with how everything was procured to stretch it as far as possible. This ended up with weeks of delays from overseas, tracking down, negotiating with vendors, and overall headaches.
My friendly mailman didn't appreciate sheet metal being delivered to my house, and some vendors refused to sell a high schooler gaseous chemicals for buoyancy, but with no car I had to get creative, so USPS freight and settling for natural buoyancy offset by pumps it was.
At the time overcoming sustained wireless transmission through water was impossible (I tried underwater zigbee and zwave to no success) so I pivoted to high-integrity shielded ethernet with a long rope for connection to the switch from the surface.
The switch connected the Arduino Mega controller for motor and bilge controls, and a first edition Raspberry Pi – one for processing 2 usb camera feeds, and the smallest windows host I could find – one for hosting the application written in Java, C, C++ that aggregated the rpi camera feeds and the control into the Arduino mega board.
In all fairness, while I learned about EE, soldering, prototyping, and building the physical controls and sensors, I had no idea how to program C++, C, or Java. I emailed several professors at random colleges who then turned me to one of their students who pretty much wrote 90% of the application and taught me where to fill in the blanks, and why those blanks needed to be filled.
We worked together to include interior-enclosure temperature, exterior-water temperature, water currents, and had later hopes of fish, algae, and moss identification (which was probably impossible at that point).
After several hundred tests in my grandparents pool over an entire summer, I was ready to drop it into the nearest lake and go underwater-robo-cop on the nearest school of fish I could find.
Unfortunately as I repeatedly dropped my submarine off the side of the dock and watched it sink to the bottom of the lake while spinning correctly in every direction to my amusement – I watched on the screen as my interior camera caught a brief flash of light inside and then a non-responsive sub completely ruined.
I pulled it out and it looked like a capacitor blew next to the cheap adhesive which allowed water into the main enclosure. I didn't mind the project seemingly imploding at that point to my surprise, though.
I had come into issues at every single turn of this project. Procuring electronics from China to spread my budget further and the challenges therein, learning electrical principals and how/why these seemingly identical components do such different things, coordinating help and resources since I knew Java/C/C++ would be out of my reach in my desired timeframe.
So while the electronics, and fish location and identification dreams, to my briefly-successful submarine were hosed (pun intended) -- my new found project management and execution abilities had reached a maturing point.
It also taught me not to cheap out on components.
Tough luck for Grandpa though, who spent most of that time standing on that same dock fishing. I always thought he might just be a lousy fisherman, yet as I write this I think there may have been another reason the fish weren't frequenting our area.