The BBC has released an official augmented-reality Sonic Screwdriver app, with four different versions of the screwdriver to choose from.
Created by Australian developer Useless Creations, which specialises in quirky augmented-reality apps (we like the dinosaur one), the app features four iterations of the Doctor's famous tool: the third and fourth (John Pertwee and Tom Baker), as well as the more recent 10th and 11th (David Tennant and Matt Smith). You can also choose from a space background or augmented reality — where you appear to be holding the screwdriver in the real world.
Each of the screwdrivers makes a different sound, taken from the TV show, and you can tilt your phone or slide your finger on the screen to change the pitch, and it even works as a flashlight.
Although, to be honest, we can't see it catching on for cosplayers. Pick it up from the iTunes App Store here.