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.

https://makerworld.com/en/@Sparrow0914