I was setting up a spare PC and needed a mouse. Deep in the recesses of my mind I remembered that I had an old Cyborg RAT7 mouse in a box in the shed after a house move. Unfortunately, one of the parts holding on the thumb rest and buttons had shattered.

Out with the calliper's, a bit of CAD and an hour later from the 3D printer I had a replacement part. (if only it was that easy, it took 3 iterations for strength and clearance).

Taking apart the mouse was more difficult, hammering out a cotter pin, tight clearances squeezing the part over a screw post, but it was installed in the end.

Original bat was 630 mah and the new bat is 4000 mah