Tennis Balls Make Good Garage Parking Sensors

A garage parking aid does not need a camera, a laser, or another app that wants firmware updates. A tennis ball on a string is still one of the better versions: cheap, visible, soft, and easy to move when the target changes.

The setup is just a ball hung from the ceiling so it kisses the windshield when the car is in the right spot. Park once with enough clearance for the garage door, bikes, stroller, shelves, and walking space. Then mark the ceiling point above the windshield contact spot and hang the ball there. The next parking attempt becomes a slow roll forward until the ball touches glass.

The useful detail is to tune for the most constrained thing, not the prettiest alignment. If the real problem is opening the rear hatch without hitting storage bins, set the ball for that. If the problem is leaving room to walk behind the car with groceries, set it for that instead.

It is almost embarrassingly low-tech. That is the point. The ball gives one clear physical signal and cannot forget its Bluetooth pairing.