I designed this to replace a missing piece of curved track from a "Santa's Christmas Special" Christmas tree train set from Density.

This is the type of train set that runs around a Christmas tree on batteries.

I can't find a huge amount of information about this product online, but there does appears to be a number of similar products and variations, so this design may be compatible with others.

If you want to print a full circle, you will need 18 curved pieces of track.

I printed with tree supports and a 5mm raft margin using Cura 4.11.0.
The raft may not be necessary (although, it was for me), but you will definitely need some kind of support.

This was designed in OpenSCAD. I've included the source files.

train_track_common.scad contains the basic components of the track which are shared between the straight piece and the curved piece.

train_track_straight.scad is the straight piece of track

train_track_curved.scad is the curved piece of track

I designed the tracks to be aesthetically similar to the originals, so the replica wouldn't stand out against them, but the design is not identical to the original pieces.

I omitted the screw hole in one of the sleepers and I didn't attempt to model the wood effect of the sleepers. I also tweaked the clip holder so that it sits flat on the print bed to avoid unnecessary supports. The sleepers on the original are hollow, but in my design they are solid, again, to avoid unnecessary supports.