Our cat Elsa needs lots of entertainment. In our last attempt to make her happy, we bought her a Flippity Fish: a plush that looks like a fish, but it starts wiggling and flipping when its body gets hit.
It looks really nice and fun, but Elsa disagrees. When it starts moving, she immediately leaves it and looks at it from a distance. I think she's scared of how much and how long it moves. To prove my theory, I took it apart and looked for ways to reduce the wiggling, or even make it remote-controllable.
So the USB-to-serial adapter arrived. I can now program the ESP-01 module, considerably smaller than the development boards I have: the WeMos D1 mini, for example, is a little too big to fit inside the small space available in the plastic enclosure.
With a bunch of jumper wires I kinda managed to connect it to an ESP-01 module. Did a first programming, then I unplugged the wires from the adapter, re-plugged the ones for the fish, and checked if it worked. It did work, but I needed a few adjustments. Unplug again, re-plug again. And every time, carefully check for mistakes.
Mildly fed up by this tedious process, I decided to build myself an adapter board. So I could plug the ESP-01 on one side, and the USB-to-serial adapter on the other. An evening and a morning later, here's the result: