Created a +2 mag extension for my plasticatto build. This is a 31mm ish extension with a large baseplate to limit it to +2 rounds. I limited it here because I know the factory Glock mag springs will work with this.
This should fit all factory Glock 17/34 mags.
These are available on my Makerworld profile along with a few other accessories that might suit your needs.
Gl19 mag compatible?
To be 100% honest, I’m not sure. I don’t have a 19 mag to test it on