I had found several other versions of the G305 base out there, but many of them had large horizontal lines in the cutouts to reduce weight, and when sliced, I found those lines were at a slight angle, resulting in either dropped bridges, or the need to print with supports, followed by a lot of post -processing. I made this remix aiming to have no horizontal bridges, and kept all cutout angles to 45 degrees - I pretty easy angle without support.
Also, I only cutout the side without the button and support - I am sure additional weight can be reduced again, but this is my first attempt at customizing it. I will post a make soon.
Update: I have added v2 - this version removes some triangles that cut through supports that will be needed for strength, but also adds additional triangles to the 'thumb' side of the mouse body too.
I am sure you can print this with a variety of materials - but I had PLA in my machine when I wanted to test it - so that is what I used first.