In late 2023, two computer science graduates in Germantown, Wisconsin, started selling a gray square about the size of a teabag. Called the Brick, it was 3D-printed in a basement. Tap your phone against it, and the apps you’ve chosen become blocked until you tap it again. The product works because of where you leave it. Stick the Brick to your fridge, and opening Instagram now involves standing up, walking to the kitchen, and holding your phone …