I designed this flexible/articulated track to suit genuine Brio train tracks.

Each joint allows ± 5 degrees of movement. The track can be printed in "one piece" then lifted off the build plate and put straight to use... or you can print the pieces separate and click them together depending on how long/flexible you need it.

I have separate files for the male/female track ends and also the centre hinge pieces. I also have a file with 16 × centre hinge pieces should you want to just print more of those to extend the flex section.

Lastly, I have STP files of each piece should you want to tweak the clearances/design.

The clearance as per the files now allow you to print at 0.20mm layer height and the hinges are nice and free after printing allowing easy articulation. This free running joint allows the track to be pulled apart and clicked back together which makes it a bit more kid proof than the live hinge types I have seen on here. Also, the length can be customised, and you can add as many or few pieces as you need.

There is also quite a bit of vertical articulation with this track too so you can create ramps as well!!