Here are some designs for measuring apps that are available now. I’m surprised how simple they are. The decibel meter design is clever because it looks quite realistic.
Here is an image showing common apps. I’m really impressed with the design of the camera, YouTube and the compass because they look really realistic.
Below I have circled one of the apps because I like the way it has a 3D looking border. The border makes it stand out from the rest of the icons.