Nothing really special about how to print this.

Except from the fact that I'd recommend leaving cooling off. This is to prevent one side from cooling faster than the other, creating internal stresses when the arches are rejoined, which can lead to cracks, as it did for me... twice...

I don't think tolerances particularly matter.

I have attached .stl, stp, and fusion files so that you can more easily adjust to fit your laptop.

The existing laptop channel width is 25mm.

Beware that any large feet or plastic protrusions from the base of the laptop may cause it to sit unsymmetrically. In my case, it turned out to be quite helpful, but you may want to make the whole thing a bit wider in your use case.