A mouse that can be easily printed as a single part, the orientations are chosen for smooth curves and surfaces for any visible part. The electronics are simply plugged in and held by latches, the lid can be opened and closed to change the battery or throw the USB dongle in ;). This model consumes just 70g PLA with the preset values. No screws or supports are needed. 

Before the part is ready for use, its very important to remove the support on the bottom, otherwise the lid will break off.

Pay attention to the pictures:

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Grasp the lid close to the axle and break the movement free while gently move forward and backward, this should not require much force but can take a minute. It has to be very tight to give it hold while printing and also to maintain the position later when you use it, so be aware to calibrate your filament well. Let me know if you encounter issues.
After the lid moves, you are fine to fit the electronics and the battery, glue the gliders on the underside so that the mouse rests well and you are done :)

No additional support is required. If you were using a bedslinger, position the mouse horizontally to the bed movement and activate tree-support (only from the bed) to prevent vibrations. You can add brim on the model to improve bed-adhesion and prevent warping (which has not happen to me).
  

Update:
V3 is now a bit less tight, im not sure about if thats really something good :D
But also the 4.Button and the Mouse wheel are also fixed, now it should work fine while depending a bit on your filament choice.
V4 has now an integrated simple detent that should hold the lid in position better.