IT IS INDEED A STRANGE LOOKING CONTRAPTION BUT MAY HAVE ACTUALLY WORKED.
I HAVE SEEN STRANGER THINGS IN THE PAST AND IN MY TEEN AGE YEARS WE MADE SOME ZIP GUNS OUT OF JUNK THAT WERE AS DANGEROUS TO THE USER AS TO THE TARGET USUALLY OURS WERE SINGLE SHOT AND USED 22 BULLETS. ONE OF MY FAVORITES SHOT BICYCLE SPOKES IT WAS A SMALLER VERSION OF A PRINCIPLE USED IN OLD MEDEVIL PROJECTLE THROWERS WHERE A FLEXIBLE PIECE OF METAL WAS PULLED BACK (COCKED) THE SPOKE WAS PLACED IN POSITION AND WHEN THE TRIGGER WAS RELEASED IT STRUCK THE BACK OF THE SPOKE AND SENT IT OUT WITH QUITE A LOT OF FORCE. SOME OF THE CONTRAPTIONS BUILT IN PRISONS ARE ALSO REMARKABLY CRUDE , SOMETIMES THEY WORK AND SOMETIMES THEY DON'T BUT THEY ALWAYS NEED A CLOSE TARGET AS THEY ARE NOT ACCURATE AND MAY INJURE THE SHOOTER AND NOT THE TARGET. I WONDER IF THE PRISONS STILL HAVE THEIR OLD COLLECTIONS OF SUCH WEAPONS AS I HAVE NOT SEEN ANY IN QUITE A WHILE.