Handguns in general are not the “sweet spot” of 3D2A. Consumer printers and the materials they can handle just can’t produce strong enough parts in the sizes that make sense for most handguns. So when it comes to handguns you basically have two reasonable choices:

1. Any of the single-shot 22LR designs. Building one of the Harlet/Harlot/Gambino/Cabfare or their derivatives is sort of a rite of passage into 3D2A. These are complete DIY builds and will teach you good fundamentals that will help you on more advanced projects.
2. A “parts kit” build where you take all the parts from a mass-produced handgun like the Glock and print your own frame. I’m personally not a fan due to the relatively high cost (cheap parts dramatically reduce reliability) and the limited knowledge/experience gained. But if you just want a range toy you can mag-dump into trash, this will get you there.

Avoid the NAG (Not-A-Glock) permanently. Avoid the NULL22 and other NAG derivatives until you have experience with a simpler full DIY build. Same for the revolver designs.

Assume your first build is just that – your first, but not your last. Keep it cheap and modest and use it as a stepping stone to reach more ambitious goals.