Rohit de Sa has an Android phone with a feature known as USB On The Go (OTG), allowing the phone to act as either a host or slave. Thus, it can interface with various USB devices such as mice, keyboards, etc. Since in his region a USB OTG cable is not easily available, Rohit went the DIY route and designed his own cable to interface phone and USB Flash drive. He wrote this short tutorial on his NutsAndBoltsAndFlyingSparks website detailing the project.
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This is great!