I was given and old laptop for parts and decided to use the reuse touchpad to make a separate touchpad to use like a mouse.

It uses and Arduino Pro Micro to get data from the touchpad via it's PS2 (old keyboard and mouse) interface. The Arduino is then able to act as a standard PC mouse (HID device) so it can used just like any other mouse on a PC. Mac or any device that can use a mouse.

I've included the a picture of the 3D design below so you can see what it's like inside.

The hardest part was designing buttons that worked reliably over the entire length of the button. There is a tiny button glued in the centre of the button pointing down and the 2 its coming off the button act as a hinge and also hold the button in place. I first tried a prototype button with a metal bar across it like a space bar has on a keyboard but I couldn't make it work reliably and it was very difficult to put together.

It took me a while to come up with a good way to fix the touchpad to the base and still be able to take it apart in the future so in the end I glued 4 little round mounts to the base of the touchpad and inserted M3 threaded brass inserts in to those. Then to fix it all together I just need 4 short M3 counter sunk bolts through the base.

It works great and I'm really pleased with the simple design.