I was looking for a Duplo helicopter for my nephew for Christmas but couldn't find one with just a helicopter so I made one. He's 3 so I wanted to keep it simple and only put 2x2 Duplo sized studs in the cockpit for a Duplo figure and made the rest kind of fisher-pricey. Works well with all the Duplo bricks I have tried with it so far. I was having some printing issues with larger objects so I also tried it at 1/2 scale which makes the studs regular lego size. I guess the printer isn't up to the tighter tolerances needed for lego because at this scale the lego parts are a bit hard to get on though they do work.

I think of my self as an artist and not an engineer so the tolerances are less than great and it may have some pretty big design and structural issues. My 1:1 Duplo print mostly clicked together and holds without glue but I had to clean and sand some of the parts a little bit more than I would have liked to make it work. Had to really sand the holes for the rotors so they would spin freely. I printed these on my UP! with the normal and .25 mm settings. Maybe with fine and .20mm settings it would work a bit better?