If you've ever had trouble drilling a perfectly straight hole, . With three concentric laser rings, it not only helps you drill straight down, but also lets you know how far you've gone.
You simply mount the BullseyeBore on your drill with its lasers facing downward and just watch the circles as you drill. The more the outside circle skews, the more off-kilter you are. It's way easier to see at a glance than spotting if your drill is just slightly tilted.
Meanwhile, the two circles on the inside—which stay mostly stationary—help you figure out how far down you've drilled. As you go deeper into the wood, the outer circle will get smaller and smaller until it eventually overlaps with one of the two smaller inner circles. The distance this indicates is proportional; the change in the outer circle's diameter is equal to the distance the drill bit has gone down.
But you don't just have to eyeball it. You can use the inner circles as a frame of reference. If the other circle and the second circle are half an inch apart when you start, for instance, you'll know you've gone down half an inch when they overlap.
Unfortunately the BullseyeBore is not on sale. Not yet anyway. The company is looking for industry partners license the tech or help bring it to market. Hopefully they can find someone soon because this is a genius idea and it belongs on every drill.