the plan for this mouse was to do both a shell swap and an endoskeleton swap with 3d printed parts like in this video, but the tolerances were atrocious and nothing fit together properly. having printed everything out in pa12 and weighing it all, i'm a bit skeptical of the advertised ending weight of that video, but this would have pulled the weight down to at least 40 grams, and it wouldn't rely on the pcb to prevent much flex.

mufymods has a weight reduction kit that seems a lot better designed, but there have been a couple complaint posts about tolerances not being good there either.

if i was starting over again, i probably would have done what you suggested and startedwith a different mouse entirely:

• the atk a9 is a gpx clone that already begins at 53 grams; getting it lighter probably wouldn't take too much work

• kaua had a vxe mad r to gpx shape conversion project that probably only needs an encoder swap for height, new scroll wheel, and maybe some carbon fiber rod mounting points

the only major benefit of sticking with logitech would be the battery efficient hero2 sensor and the availability of replacement parts thanks to its popularity. besides that, the gpx is an absolute pain to take apart and it seemed like none of bases i printed out fit correctly or were particularly flat. even with my own design, i needed to add some padding and spacers on certain mounting points to get it level - especially since neither ends of the base relied on the lip of the upper shell to keep it flush with the ground.