An original gpx mouse weighs 63 grams

• Upper PCB: around 3 grams

• Lower PCB: around 6 grams

• Ribbon cable: around .5 grams

• Left and right trigger: 3 grams each

• Shell cover: 13.1 grams

• Bottom cover: 8.3 grams

• Endoskeleton: 7.3 grams

• Magnetic puck: 7 grams

• Magnetic wireless charging pads: 2 grams

• Battery: 6 grams

• Side buttons: 1.5 grams

• Screws and Misc: around 4 grams

By removing the puck and the pads, you can eliminate 9 grams very easily. 

With a 3D-printed bottom cover, you can eliminate 4 grams.

With a heavily trimmed endo skeleton, you can eliminate 1.5 grams.

With light sanding on the inside of the shell cover, you can eliminate .5 grams.

This will get you close to 48.27 grams.