About this 3D model

The Duplo train tunnel is no longer sold by Lego bricks“ , and it seems somewhat overpriced on the secondary market. So my children finally have their tunnel! And it can also be a bridge if you have the drawbridge parts: It's the same height! The image above is from my first version; since then, I've added internal spacers to keep the rails centered within the tunnel (otherwise, the train might collide with the walls). I made it without supports!