I'm doing some initial research for an embedded device project I have in mind, and I'd like some help getting an idea of viable technologies which would be necessary to achieve this. I'm not an engineer, merely an electronics experimenter and a amateur hardware hacker who's done some beginner's experimentation with Arduino and Raspberry Pi.
My question is this: how would I go about building an embedded device which shows up as a flash drive via USB, but which contains no hard drive or flash drive of its own; it would not be any form of RAID system, but what it would do is aggregate other USB/SD card devices plugged into it into a virtual drive with specialized virtual folders. When the drive/hub is plugged into a PC, each flash drive or SD card plugged into it would show up as a virtual folder which would act like any regular windows folder. Each virtual folder's name would essentially be the volume name of that device, and changing the folder name would rename the volume name of plugged-in flash drive.
What combination of hardware/software/OS would I need to build such a device? I was thinking of using a Raspberry Pi or BeagleBoard as a base, or even a CubieBoard if I needed sufficient power.