Not sure if this will help at all, but if you can find out in the /dev directory of your filesystem which entry is your printer, can't you try doing
chmod a+rwx entryname
I once had almost the exact same problem but with a screensaver - no user except root could get it to work. Fix was to go into the /dev of my filesystem and set the Nvidia0, Nvidia1, Nvidia2 etc. devices to a+rwx using the above commandline...
Maybe if you do the same, but for the /dev entry for your printer, it might work for other uses except root?