We’ll be honest. When we first heard about a mouse, we weren’t convinced. The argument was that business people weren’t familiar with computers. That didn’t ring true since every business person in the last century had at least seen a typewriter keyboard, but most of them had never seen a mouse before the 1980s. The mouse has since become totally ubiquitous, so presumably, it was the right choice. However, if you are a serious touch typer, it is annoying to have to move your hands off the keyboard to a different location each time. There are several solutions for that, but the oldest one is probably the trackball. Ploopy is an open source trackball you can build yourself and it looks pretty capable.

While we aren’t wild about the name, Ploopy looks pretty good and is one of those projects that would have been very difficult ten years ago. It requires two PC boards. Those used to be hard to get. It also requires some very customized plastic parts. Getting a handful of plastic parts made used to be hard, too. But now you probably have a 3D printer that is just begging for something to do.

Modern electronics also helps the design. An ATMega32U works as the processor and an optical sensor watches the ball for motion. Speaking of the ball, apparently, it is a common miniature snooker ball. The designer sells a kit of parts — or at least will sell them. However, the details provided for sourcing your own parts is among the best we’ve ever seen. Where some bill of material lists will say something like M3x12 flat countersunk machine screw, the Ploopy wiki has the following details:

M3

0.5 mm thread pitch

Any length between 8 mm and 16 mm

5.6 mm head diameter

1.65 mm head height

90-degree countersink angle

Short of providing an actual link to the McMaster catalog, we aren’t sure how much more than could specify. Well, they didn’t tell us what type of metal the screw should be but now we are just being nit picky.

The 3D shape of the enclosure looks great. They use threaded inserts to thread the holes, so that should be pretty durable. The resulting trackball looks totally professional. Granted, you probably could run down to the store and buy a nice trackball for a fraction of the cost of this — especially if you assign a value to your time. But still, there’s something to be said for building something you’ll use a lot and that’s hard to price.

Oddly enough, this isn’t the first time we’ve seen a billiard ball pressed into service like this. At least they are cheap and easy to obtain.