As this was my first 3s quad and the angle on the original design was a bit steep with 45° I redid it from scratch in openscad for various angles.

The ring is also thinner and should be able to just stretch over the camera without the need for any cutting as instructed with original design.

Note: 20 is about the lowest you can go without adjusting the other parameters further.

You can probably also use this for other similiar quads with standoffs far enough apart to fit a cam in between by adjusting the settings :)