Here is a device that turns your smartphone into a crosshair laser level: the RYOBI Laser Level Device + Phone Works App lets you use your smartphone for level detection. You will see images and measurements on your smartphone screen. The companion app lets you capture, store, and send data. This product relies on your smartphone’s sensors for level detection. You do have the option to connect your phone to a tripod to use it more easily.
The Laser Level Device is optimized for iOS and Android devices. It can be used indoors/outdoors. It is compact and lets you put your smartphone to good use when taking on all kinds of home projects. The device sets you back under $40 at this time.[Source]