Impossible Teaser, Mr. Gogo Puzzles

305 pieces.  This was as difficult as any Stave, and a lot of fun.  My only complaint is that the pieces don't fit back in the box now and I have no idea how to pack them away sufficiently compactly!  5/5

Starting out

Almost there: these layers stack on each other, attached by two double-layered pieces

Final result, whew