This is just the inner border for Ninco slot tracks. This works only with the inner curve (I think it has a 45ยบ angle). See pictures for further reference.
The piece is flat on both sides for easy printing. You can print it at 10% infill and in your prefered material and 0.2 to 0.3 layer height. I chose ABS just for the colour and finish.
ninco_inner_curve.stl | 15.7KB |