I think it's important to keep the gantry with angles as close to 90 degrees as possible (I guess it can be compensated for in software, but better to be precise).

The construction of angles keeps the angles close to 90 degrees, but it's short, so I think it won't be able to keep angles precise enough.

I got a sturdy mechanical angle, and now I need to connect it to the gantry. 3D printing to the rescue!

Here is how it looks connected to the angle:

I need to tighten it onto the frame, and what's better for that than tried and true zipties. Lucky I have a tensioner tool, couldn't do it by hand:

And the end result is: