[Elgatoandaluz] has posted this guide on how to tear apart a standard optical mouse and build a custom trackball. He’s using a ping pong ball , mounted above the laser as the trackball itself, which seems like it would be a little lite, but functional. The case is scrap cardboard. We really like that you could toss this together relatively quickly and have a custom layout. He recommends using Sakasa Mouse for inverting the axes and X-control for mapping the buttons(direct download).
Being hackers, sometimes we just want to hack something together, not engineer it. This projector is a great example. Made mostly out of cardboard and duct tape (or duck tape if you prefer). He picked up a 12v LED array, a cheap fresnel lens, an LCD from a “back up monitor” and a focusing lens taken from a magnifying glass. Sure, we’ve seen better, much better. But seeing an evenings worth of feverish wire twisting and taping is always pleasant. It may look pretty dim in the video, it may be as well, but keep in mind that it is common for them to appear much brighter in person or if shot with a night setting on a digital camera.
A quick lesson on being a good parent. If you make an awesome electronic cart out of trash that may not necessarily be stable, or even fully capable of stopping once it gets going, you MUST put your children on it and insist that they drive. Did we mention that the system is full acceleration or no acceleration? Indeed, it is. There isn’t a writeup, and one really isn’t needed. This is dead simple. The parts list will explain most of what is going on, but the look of doubt and fear on the kids face is what really makes this hack worth it. Or is that possibly a look that says “what are you looking at?”