Yesterday, Luke covered the NSW Police's press conference discussing the dangers of the "Liberator", a single-shot gun one can create themselves with a CAD file and 3D printer. Police Commissioner Andrew Scipione mentioned during the presser that the organisation had printed a few of the weapons itself and tested them, the results of which you can view in this video.
Vision of the manufacturing process starts at the 25-second mark, with test firings shown 45 seconds in. You'll see the weapon does indeed work, though after witnessing the aftermath -- or "catastrophic failure", as described by Scipione -- I wouldn't be particularly keen to pull the trigger on one.
Going from the video, the weapon was tested at extremely close range -- we're talking centimetres here -- even so, the damage such a benign-looking piece of plastic can do is surprising.