3D printing is unquestionably amazing, but it does have some downsides. Most hobby 3D printers use the fused-filament fabrication (FFF) process, which is affordable but somewhat imprecise. That makes it great for making enclosures and prototype mechanical parts, but usually unsuitable for parts that need to interface together smoothly. Gears are a great example of those kinds of parts, because they only work well if they mesh well. In his newest video, YouTuber smbakeryt covers multiple stepper motors, methods of driving them, and 3D-printed gears.
In the video, smbakeryt tests both Nema 17 and Nema 11 stepper motors, and explains the benefits and drawbacks they have compared to servos or gearmotors. He also shows how they can be controlled with a Raspberry Pi or even just a low-cost Microchip ATtiny85 microcontroller. Finally, he demonstrates a couple of different 3D-printed gear mechanisms, including one with 18 individual gears. If you want to learn more about 3D-printing gears and how to drive them, this is a great video to watch.