Originally Posted by daveps
Apologies for dredging an oldish topic up but if you want to mount a USB stick via OTG cable and do not want to root you can use an app called Nexus Media Importer. Only snag is it costs cash, there is a free app Nexus Photo Viewer which you can use to verify that your OTG cable and stick are compatible before purchasing the full blown importer.
Disclaimer : I haven't used this, I use StickMount as I am rooted.
I have used this method without the rooting and it works, very well!