ZMK
I had been using a ergonomic split keyboard for almost a year and the experience was great in general. I got to customize keys to be placed where I wanted them to be: putting the harder-to-reach keys such as backspace to be closer to my pinky, creating a symbol layer that basically moves the number row to my home-row with the help of my left thumb, which had been previously unassigned to type any keys, and various other customization.
However, there was a quirk to this awesome keyboard: it requires a usb cable between the computer and itself and a cable to connect the two halves. This was generally OK to me, but as I brought the keyboard to school everyday, the cables usually got in the way on my desk. After months of getting bumped in my backpack, one half of keyboard eventually broke. Thus, I decided to build my own keyboard. After some extensive research, I settle down on the model, lily58, which has a similar layout as my older one but with fewer keys that I had never used. I also learned about the free and open-source firmware ZMK, which dedicates to building wireless split keyboard, and I immediately fell in love with it. It was a dream of mine to have a wireless split keyboard, because I thought it could never be technically possible to achieve.
I gathered the pieces to be assembled for this new keyboard and started soldering the components at school. The diodes were the hardest to solder, as they were cylindrical and tiny, making them harder to be fixed in place using tweezers. Then there was the hot-swappable Kailh sockets, which were much easier because of their bigger size and snappiness on the PCB. After soldering the micro-controller, I flashed the firmware on the keyboard and built the case after school. Since I was a complete beginner at soldering, I expected to have some soldering errors on the PCB. But to my surprise, it worked right out of the box! Now, I have a fully-functioning wireless split keyboard and it is such a dream come true!