A cable wrap and cover to keep usb charging cables tamed. There are slots at each end to allow the cord ends to be exposed with the cover on so a long cord may be effectively shortened. I added a foot to the cover to prevent it from rolling.  Most usb cord ends can be tucked into the bore of the core. 

I'm sure there are other similar sized cords that can be stored on the core and covered, protected, or concealed. 

I know someone with enough time and creativity can turn the simple cover into a more interesting/ technical/ sci-fi looking generator or similar aesthetic.