Well its a old design, Used by Gamblers if i remember right.
Well since it has internal Metal cylinders it wont explode i guess if the dimensions are right.
But how are they being kept inside? In the video he just pots them from the top so isnt it able to just fall out? lets stand if you fire :P

But this one isnt truely totaly 3D printed either, But i guess it will be better then the liberator in the mind of being reshootable and more then 1 bullet.